Docs: Restructuring and new layout

This patch implements a set of user-experiences aimed
changes.It modifies the documentation structure and
switches to a more reactive design for the rtd theme.

* The documentation layout has been redesigned to be more
  intuitive,easier to maintain and and scale.
* The landing page introduces a new dashboard.
* Introduced dedicated space for release documents, and
  changelog has been modified to directly source content
  from referenced documents.
* Added quick-link navigation for items that need emphasis.
* Relevant design documents can now be grouped in suf-folders.
* There is dedicated space for custom platform, and third
  party tools documents.
* Wildcard and regex matching has been introduced to indexes.

Change-Id: Ib02d17d5d26187d397ba17317788cf2a01401b07
Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/docs/contributing/coding_guide.rst b/docs/contributing/coding_guide.rst
new file mode 100644
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@@ -0,0 +1,79 @@
+##############################
+Yet another coding standard :)
+##############################
+
+.. Warning::
+
+    Every rule has an exception so if you disagree or dislike then reach out!
+
+The coding style of TF-M project is based on
+`Linux coding style <https://www.kernel.org/doc/html/v4.10/process/coding-style.html>`__
+but there are updates for domain specific conventions as listed below.
+
+TF-M also reuses code from other SW projects, e.g. ``CMSIS_5``, which
+means some areas of code may have different styles. We use common sense approach
+and new code may inherit coding style from external projects but it needs to
+remain within clear scope.
+
+The guidance below is provided as a help. It isn't meant to be a definitive
+list.
+
+As implied in the :doc:`contributing guide </docs/contributing/contributing>`
+maintainers have the right to decide on what's acceptable in case of any
+divergence.
+
+.. Warning::
+
+    Text files do not fall within these rules as they may require different formatting.``
+
+****************
+Consistent style
+****************
+The code needs to be consistent with itself, so if existing code in the file
+violates listed coding style rules then it is better to follow existing style
+in the file and not break consistency by following the rules listed here.
+
+You may need to add a comment in the commit description to clarify this.
+
+List of rules
+=============
+
+- Use 4 spaces indentation. No tabs.
+- Use ``lower_case_with_underscore`` for filenames, variable and function names.
+- Use standard types e.g. ``uint32_t``, ``uint16_t``, ``uint8_t``, ``int32_t``
+  etc.
+- Use ``uintptr_t`` type when representing addresses as numbers.
+- Use static for all private functions and variables.
+- Use void argument if your function doesn't contain any argument.
+- Use C90 ``/* */`` for comments rather than C99 ``//``
+- No trailing spaces in code.
+- Max 80 characters length. Text files are exception as stated above.
+- Open curly brace ``{`` at the same if/else/while/for/switch statement line.
+- Use curly braces ``{ }`` for one line statement bodies also.
+- Put open curly brace in the line below the function header.
+- Order function parameters so that input params are before output params.
+- Declare local variables at the beginning of the function.
+- Define macros in all caps i.e. ``CAPITAL_WITH_UNDERSCORE``.
+- Use typedefs **ONLY** for function prototype declarations.
+- Type definitions in ``lower_case_with_underscore`` ended by ``_t``.
+- Do not use typedef for other constructs as it obfuscates code.
+- Do not use bitfields.
+- Use static for all global variables to reduce the variable scope.
+- Use enumeration for error codes to keep the code readable.
+- Use descriptive variable and functions names.
+- Put the correct license header at the beginning of the file.
+- Keep the files (.h/.c) self-contained, i.e. put include dependencies in the
+  file.
+- Put appropriate header define guard in .h files: ``__HEADER_NAME__``.
+  Any divergence from this rules should be clearly documented.
+- In a .c file, #include it's own header file first.
+- Document all the public functions in the header file only.
+- Document all the private functions in the source file only.
+- Add "extern C " definition for C++ support in the header files.
+- In the switch statement, aligned cases with the switch keyword.
+- For enums, use upper case letters with digits and underscore only.
+- Do not code while eating.
+
+--------------
+
+*Copyright (c) 2018-2020, Arm Limited. All rights reserved.*
diff --git a/docs/contributing/contributing.rst b/docs/contributing/contributing.rst
new file mode 100644
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--- /dev/null
+++ b/docs/contributing/contributing.rst
@@ -0,0 +1,69 @@
+Contributing
+============
+
+Contributions to the TF-M project need to follow the process below.
+
+.. Note::
+
+   Please contact :doc:`maintainers </docs/contributing/maintainers>` for any
+   questions.
+
+- Subscribe to `TF-M development
+  <https://lists.trustedfirmware.org/mailman/listinfo/tf-m>`_ if not subscribed
+  already.
+- Refer to the `Roadmap
+  <https://developer.trustedfirmware.org/w/tf_m/planning>`_ or send a mail to
+  the tf-m@lists.trustedfirmware.org to check if this work is already
+  planned/progresses elsewhere.
+- Create a task in `Phabricator
+  <https://developer.trustedfirmware.org/maniphest>`_, put as many details as
+  possible in the description. Add 'Trusted Firmware M' in the 'Tags' field.
+- For non-trivial changes, need to follow the design proposal process
+  :doc:`Design Proposal Process </docs/contributing/tfm_design_proposal_process>`
+  for the TF-M project.
+- After the design has been accepted by the maintainer(s), a corresponding
+  patch should be posted; follow guidelines below:
+
+  - Clone the TF-M code on your own machine from `TF-M git repository
+    <https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git>`_.
+  - Follow the :doc:`SW Requirements </docs/getting_started/tfm_sw_requirement>`,
+    :doc:`Build Instructions </docs/getting_started/tfm_build_instruction>` and
+    :doc:`Coding Guide </docs/contributing/coding_guide>` for the TF-M project.
+  - Make your changes in logical chunks to help reviewers. Each commit should
+    be a separate review and either work properly or be squashed after the
+    review and before merging.
+  - Update documentation in docs/ folder if needed.
+  - Test your changes and add details to the commit description.
+  - The code is accepted under :doc:`DCO </docs/contributing/dco>`, Developer
+    Certificate of Origin, so you must add following fields to your
+    commit description:
+
+    .. code-block:: text
+
+       Author: Full Name <email address>
+       Signed-off-by: Full Name <email address>
+
+    .. Note::
+
+       Sign off authority needs to adhere to the [DCO](./dco.txt) rules.
+
+  - You may add other fields in the commit message. Need to add the Task ID link
+    in the comment for the commit.
+  - Submit your patch for review.
+
+    .. code-block:: shell
+
+       git push ssh://review.trustedfirmware.org:29418/TF-M/trusted-firmware-m.git HEAD:refs/for/master
+
+- Add relevant :doc:`maintainers </docs/contributing/maintainers>` for reviewing
+  the patch.
+- You may be asked to provide further details or make additional changes.
+- You can discuss further with maintainer(s) by directly over email if
+  necessary.
+- Once the change is approved by maintainers, the patch will be merged by the
+  maintainer.
+- Mark the task as 'resolved' after patch is merged.
+
+--------------
+
+*Copyright (c) 2017-2020, Arm Limited. All rights reserved.*
diff --git a/docs/contributing/dco.rst b/docs/contributing/dco.rst
new file mode 100644
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+
+###############################
+Developer Certificate of Origin
+###############################
+
+.. include:: /dco.txt
+   :literal:
+
+
+-----------
+
+*Copyright (c) 2019, Arm Limited. All rights reserved.*
diff --git a/docs/contributing/index.rst b/docs/contributing/index.rst
new file mode 100644
index 0000000..f21a1c7
--- /dev/null
+++ b/docs/contributing/index.rst
@@ -0,0 +1,14 @@
+Contributing
+============
+
+.. toctree::
+    :maxdepth: 1
+    :caption: Contents
+    :glob:
+    :numbered:
+
+    *
+
+--------------
+
+*Copyright (c) 2020, Arm Limited. All rights reserved.*
diff --git a/docs/contributing/lic.rst b/docs/contributing/lic.rst
new file mode 100644
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+++ b/docs/contributing/lic.rst
@@ -0,0 +1,10 @@
+
+#######
+License
+#######
+
+.. include:: /license.rst
+
+-----------
+
+*Copyright (c) 2019, Arm Limited. All rights reserved.*
diff --git a/docs/contributing/maintainers.rst b/docs/contributing/maintainers.rst
new file mode 100644
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--- /dev/null
+++ b/docs/contributing/maintainers.rst
@@ -0,0 +1,77 @@
+Maintainers
+===========
+
+Trusted Firmware M is a community maintained project. Contributions can only
+be approved and merged by the maintainers listed below.
+Sub-maintainers' approval is required for their specific areas of ownership.
+
+Contributions must follow the instructions in
+:doc:`Contributing Guidelines </docs/contributing/contributing>`.
+
+Main maintainers
+----------------
+
+Abhishek Pandit
+    :email: `abhishek.pandit@arm.com <abhishek.pandit@arm.com>`__
+    :github: `abhishek-pandit <https://github.com/abhishek-pandit>`__
+
+Ashutosh Singh
+    :email: `ashutosh.singh@arm.com <ashutosh.singh@arm.com>`__
+    :github: `ashutoshksingh <https://github.com/ashutoshksingh>`__
+
+Miklos Balint
+    :email: `miklos.balint@arm.com <miklos.balint@arm.com>`__
+    :github: `wmnt <https://github.com/wmnt>`__
+
+Sub-maintainers
+---------------
+
+Bootloader
+~~~~~~~~~~
+
+Tamas Ban
+    :email: `Tamas.Ban@arm.com <Tamas.Ban@arm.com>`__
+    :github: `tamban01 <https://github.com/tamban01>`__
+
+Secure Storage (ITS & PS)
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Jamie Fox
+    :email: `jamie.fox@arm.com <jamie.fox@arm.com>`__
+    :github: `jf549 <https://github.com/jf549>`__
+
+Crypto
+~~~~~~
+
+Soby Mathew
+    :email: `Soby.Mathew@arm.com <Soby.Mathew@arm.com>`__
+    :github: `soby-mathew <https://github.com/soby-mathew>`__
+
+SPM & IPC
+~~~~~~~~~
+
+Ken Liu
+    :email: `Ken.Liu@arm.com <Ken.Liu@arm.com>`__
+    :github: `KenLSoft <https://github.com/KenLSoft>`__)
+
+Mate Toth-Pal
+    :email: `Mate.Toth-Pal@arm.com <Mate.Toth-Pal@arm.com>`__
+    :github: `matetothpal <https://github.com/matetothpal>`__)
+
+Audit Log
+~~~~~~~~~
+
+Anton Komlev
+    :email: `Anton.Komlev <Anton.Komlev@arm.com>`__
+    :github: `Anton-TF <https://github.com/Anton-TF>`__
+
+Attestation
+~~~~~~~~~~~
+
+Tamas Ban
+    :email: `Tamas.Ban@arm.com <Tamas.Ban@arm.com>`__
+    :github: `tamban01 <https://github.com/tamban01>`__
+
+--------------
+
+*Copyright (c) 2017-2020, Arm Limited. All rights reserved.*
diff --git a/docs/contributing/tfm_design_proposal_process.rst b/docs/contributing/tfm_design_proposal_process.rst
new file mode 100644
index 0000000..0be4d04
--- /dev/null
+++ b/docs/contributing/tfm_design_proposal_process.rst
@@ -0,0 +1,156 @@
+Design proposal process
+=======================
+
+:Author: Gyorgy Szing
+:Organisation: Arm Limited
+:Contact: Gyorgy Szing <gyorgy.szing@arm.com>
+
+Purpose and Content
+-------------------
+This document describes the steps of adding/changing Trusted Firmware design. It
+specifies:
+
+  - The documentation format to be used.
+  - The information which shall be captured.
+  - The steps of the process.
+  - The location where the information shall be captured during the process.
+
+General
+-------
+The Trusted Firmware project uses the
+`reStructuredText <http://docutils.sourceforge.net/rst.html>`_ format with
+`Sphinx <http://www.sphinx-doc.org/en/master/usage/restructuredtext/index.html>`_
+extensions for documentation. Design documents shall be captured in this format.
+
+Design documents are kept under version control at the project's
+`Gerrit server <https://review.trustedfirmware.org>`_. All decisions made and
+important information gathered during the design discussion, which is  not part
+of the design document shall be captured as Gerrit comments or notes for
+archiving purposes. To meet this requirement this process encourages the use of
+the Gerrit web UI for communication.
+
+
+Status of a document
+---------------------
+The status of the document is captured in a *reST filed* called *Status*.
+Bibliographic fields like the *Status* shall be kept near to the top of the
+document after the document title.
+
+Example document fragment::
+
+    TF-M Crypto Service design
+    --------------------------
+
+    :Author: Antonio de Angelis
+    :Organization: Arm Limited
+    :Contact: Antonio de Angelis <antonio.deangelis@arm.com>
+    :Status: Draft
+
+Design documents are kept in three different sections of the documentation
+reflecting the status of the document. The status of the document determines
+the section it is in. Open (*Draft* and *Detailed* status) and accepted design
+documents shall be put to the ``docs/design_documents`` directory.
+
+.. important::
+  - 'Author' and 'Organization' can be *OPTIONAL* but at least one of them is
+    *MANDATORY*.
+  - 'Contact' is *MANDATORY* and must be valid for contacting with 'Author'
+    or 'Organization'.
+  - 'Status' is *OPTIONAL* if the design document is managed under a version
+    control tool. In this 'Status' field not available case, a guideline can be:
+
+    - No review comments given design is a *Draft* design.
+    - Positive review comments given design is a *Detailed* design.
+    - Merged design is an *Accepted* design.
+
+Preparation
+-------------
+In order to work on TF-M documentation the TF-M git repository has to be
+available locally. Setting up the documentation tools will allow pre-viewing the
+documentation file in preparation.
+For information on what tools are needed please refer to
+:doc:`sw requirements </docs/getting_started/tfm_sw_requirement>`. To see how to get
+a local copy of the TF-M repository please see
+:doc:`build instructions </docs/getting_started/tfm_build_instruction>`
+
+Process steps
+-------------
+
+- Write the design proposal in the format that is described in this document
+  with the *Status* set to *Draft* if *Status* field is provided. Put it to the
+  ``docs/design_documents`` directory and create a pull request.
+- Start an e-mail thread on the
+  `TF-M mailing list <mailto:tf-m@lists.trustedfirmware.org>`_ for discussing
+  the proposal.
+- Build initial consensus within the community about the proposed design
+  change, rework it according to the feedbacks and identify members who would
+  like to participate in the detailed review.
+- When the "short list" of members who are willing to participate in the
+  detailed review is established, set the *Status* field to *Detailed* if
+  *Status* field is provided and push the change to Gerrit.
+- Add the members of the "short list" to the Gerrit review as reviewers.
+- The detailed discussion then takes place in the Gerrit review and gets
+  recorded there.
+  Additional changes are submitted as new commits to the review.
+- When the proposal is accepted and *Status* field is provided, the *Status*
+  field is set to *Accepted* and update the change then get merged.
+
+.. uml::
+
+  @startuml
+  !define DRAFT_DIR **docs/design_documents/**
+  !define REJECTED_DIR **docs/design_documents/rejected/**
+  !define GERRIT_URL https://review.trustedfirmware.org
+  !define GERRIT_LINK [[GERRIT_URL trustedfirmware.org]]
+  !define MAINTAINER_RST_URL https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/docs/maintainers.rst
+  !define TFM_MAILING_LIST mailto:tf-m@lists.trustedfirmware.org
+  !define NO_DECISION **no**
+  !define YES_DECISION **yes**
+  !define STATUS_DRAFT **Draft**
+  !define STATUS_DETAILED **Detailed**
+  !define STATUS_REJECTED **Rejected**
+  !define STATUS_ACCEPTED **Accepted**
+
+  title Design Proposal Process
+
+  start
+  :Create first draft.in [[http://docutils.sourceforge.net/rst.html ReST format]];
+  :Set it's available 'Status' field to STATUS_DRAFT.;
+
+  :Add your document under DRAFT_DIR.;
+  :Create pull-request at GERRIT_LINK.;
+  partition "Initial review." {
+      :Start an e-mail thread at [[TFM_MAILING_LIST tf-m mailing list]].;
+      repeat
+          :Build initial consensus within the
+           community about the proposed design change.;
+          :Gather developers interested in detailed review.;
+       repeat while (Ready for detailed review?)
+  }
+
+  partition "Detailed review." {
+      :Set available 'Status' field to STATUS_DETAILED.;
+      :Add reviewers to pull request.;
+
+      repeat
+         :Discuss design in Gerrit comments/notes.;
+         :Log the result of discussions over
+          other communication channels
+          as Gerrit comments/notes.;
+         :Push new document version if needed.;
+      repeat while (Consensus reached?)
+  }
+
+  if (Design is accepted?) then (STATUS_ACCEPTED)
+      :Sets available 'Status' field to STATUS_ACCEPTED.;
+      ://Submit// the pull-request.;
+  else (STATUS_REJECTED)
+  endif
+
+  stop
+
+  @enduml
+
+--------------
+
+*Copyright (c) 2019-2020, Arm Limited. All rights reserved.*