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/index.rst b/docs/platform/ext/index.rst
index 4aea392..22861e5 100644
--- a/docs/platform/ext/index.rst
+++ b/docs/platform/ext/index.rst
@@ -1,18 +1,8 @@
-Supported Platforms
-===================
+TF-M Platforms
+==============
 
 .. toctree::
-    :maxdepth: 1
-    :caption: Information
-
-    /platform/readme
-    readme
-    /platform/ext/platform_introduction.rst
-    /platform/ext/platform_deprecation.rst
-    /platform/ext/platform_provisioning.rst
-
-.. toctree::
-    :maxdepth: 1
+    :maxdepth: 2
     :caption: arm
     :glob:
 
@@ -33,21 +23,21 @@
     target/cypress/psoc64/index
 
 .. toctree::
-    :maxdepth: 1
+    :maxdepth: 2
     :caption: STM
     :glob:
 
     target/stm/index
 
 .. toctree::
-    :maxdepth: 1
+    :maxdepth: 2
     :caption: Nordic
     :glob:
 
     target/nordic_nrf/**
 
 .. toctree::
-    :maxdepth: 1
+    :maxdepth: 2
     :caption: Laird Connectivity
     :glob:
 
@@ -60,6 +50,13 @@
 
     target/nuvoton/**
 
+.. toctree::
+    :maxdepth: 1
+    :caption: Rules and processes
+
+    platform_deprecation.rst
+    platform_provisioning.rst
+
 --------------
 
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