docs: Documentation restructure

- Change main index structure
- Sort out integration and porting guidelines
- Resort table with releases
- Add Tools section. To be adjusted further for tf-m-tools

Intention to minimise files movement to simplify review process.
Affected files shall be moved later after the new structure agreement.

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I0352bebabe09d4f7b5e8848ee620c0cea6881c94
diff --git a/docs/platform/ext/platform_introduction.rst b/docs/platform/ext/platform_introduction.rst
index 656e1aa..be7e268 100644
--- a/docs/platform/ext/platform_introduction.rst
+++ b/docs/platform/ext/platform_introduction.rst
@@ -1,6 +1,6 @@
-######################
-Platforms introduction
-######################
+###################
+Supported Platforms
+###################
 
     - Olympus system
 
@@ -63,7 +63,3 @@
 
 The document :doc:`Platform Deprecation and Removal </platform/ext/platform_deprecation>`
 lists the deprecated platforms planned to be removed from upstream.
-
---------------
-
-*Copyright (c) 2017-2022, Arm Limited. All rights reserved.*