Docs: Bunch of small changes in documentation

- Move and rename requirements_docs.txt under /docs folder, preparing for RtD
- Update release process with a note of a branch life-time
- fix typos in 'note' directives

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I370acfbcd7a3d5c2e09ab84702e75b7cb049db35
diff --git a/docs/building/documentation_generation.rst b/docs/building/documentation_generation.rst
index 44ed546..967c338 100644
--- a/docs/building/documentation_generation.rst
+++ b/docs/building/documentation_generation.rst
@@ -19,7 +19,7 @@
     - Graphviz dot v2.38.0 or later
     - PlantUML v1.2018.11 or later
     - Java runtime environment v1.8 or later (for running PlantUML)
-    - Sphinx and other python modules, listed in ``tools/requirements_docs.txt``
+    - Sphinx and other python modules, listed in ``docs/requirements.txt``
 
 Additionally, for PDFs format:
 
@@ -51,7 +51,7 @@
             # Install the required Python modules
             pip3 install --upgrade pip
             cd trusted-firmware-m
-            pip3 install -r tools/requirements_docs.txt
+            pip3 install -r docs/requirements.txt
 
     .. group-tab:: Windows
 
@@ -77,7 +77,7 @@
             # Install the required Python modules
             pip3 install --upgrade pip
             cd trusted-firmware-m
-            pip3 install -r tools\requirements_docs.txt
+            pip3 install -r docs\requirements.txt
 
 ***************************
 Build TF-M Reference Manual
@@ -222,4 +222,4 @@
 
 --------------
 
-*Copyright (c) 2017-2021, Arm Limited. All rights reserved.*
+*Copyright (c) 2017-2023, Arm Limited. All rights reserved.*
diff --git a/docs/integration_guide/platform/documenting_platform.rst b/docs/integration_guide/platform/documenting_platform.rst
index 563307f..d0c4284 100644
--- a/docs/integration_guide/platform/documenting_platform.rst
+++ b/docs/integration_guide/platform/documenting_platform.rst
@@ -38,7 +38,7 @@
 - An explicit platform name is preferred in a vendor's TOCtree instead of use of
   platform's title by default.
 
-.. note:
+.. note::
   Do not forget to update the summary file after adding a new platform
   `/docs/platform/platform_introduction.rst` included into TF-M introduction.
 
diff --git a/docs/integration_guide/services/tfm_attestation_integration_guide.rst b/docs/integration_guide/services/tfm_attestation_integration_guide.rst
index 644d593..92972ec 100644
--- a/docs/integration_guide/services/tfm_attestation_integration_guide.rst
+++ b/docs/integration_guide/services/tfm_attestation_integration_guide.rst
@@ -479,7 +479,7 @@
   initial attestation key. The key identifier can be used as ``kid`` parameter
   in COSE header. Optional.
 
-.. note:
+.. note::
 
    Asymmetric initial attestation and symmetric initial attestation may share
    the same HAL APIs in future development.
diff --git a/docs/releases/release_process.rst b/docs/releases/release_process.rst
index 9b3b011..fca13c0 100644
--- a/docs/releases/release_process.rst
+++ b/docs/releases/release_process.rst
@@ -62,6 +62,12 @@
 Although this document specifies the release cadence, this does not preclude
 an adhoc release for specific project requirements.
 
+.. note::
+  When a new release starts the previous release branch obsoletes and is
+  a subject for removal as shown for `v1.1.x` on the diagram above.
+  At any moment only the latest release branch is maintained.
+  The release tags will point to a commit in detached head state.
+
 Release Version Scheme
 ----------------------
 
@@ -76,4 +82,4 @@
 
 --------------
 
-*Copyright (c) 2020, Arm Limited. All rights reserved.*
+*Copyright (c) 2020-2023, Arm Limited. All rights reserved.*
diff --git a/docs/requirements.txt b/docs/requirements.txt
new file mode 100644
index 0000000..4678dc5
--- /dev/null
+++ b/docs/requirements.txt
@@ -0,0 +1,10 @@
+graphviz
+Jinja2>=3.0.2
+latex
+Sphinx==4.2.0
+m2r2
+sphinx-rtd-theme>=1.0.0
+sphinxcontrib-plantuml==0.22
+sphinxcontrib-svg2pdfconverter==1.1.1
+sphinx-tabs==3.2.0
+docutils==0.16