Docs: Clean and restructure the Integration guide

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I8dca6e3d5cf5cae3a5cd3dc8f2b1e518ab3c20cf
diff --git a/docs/integration_guide/platform/index.rst b/docs/integration_guide/platform/index.rst
index 9fd2f2c..c76e327 100644
--- a/docs/integration_guide/platform/index.rst
+++ b/docs/integration_guide/platform/index.rst
@@ -1,12 +1,15 @@
-Porting to a new platform
-=========================
+#####################
+Adding a new platform
+#####################
 
 .. toctree::
     :maxdepth: 1
 
+    platform_folder.rst
+    platform_ext_folder.rst
     porting_TFM_to_a_new_hardware
-    /platform/readme
-    /platform/ext/readme
+    platform_provisioning.rst
+    platform_deprecation.rst
 
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