Docs: Update code structure doc

- fix the number of CPU to 8 to avoid Sphinx crash in OpenCI

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I4f05857a639ec2609f5b21cb739a6e91e5372fc0
diff --git a/docs/integration_guide/platform/index.rst b/docs/integration_guide/platform/index.rst
index a02134e..ff3ed0b 100644
--- a/docs/integration_guide/platform/index.rst
+++ b/docs/integration_guide/platform/index.rst
@@ -1,3 +1,5 @@
+.. _adding_platform:
+
 #####################
 Adding a new platform
 #####################
@@ -5,13 +7,10 @@
 .. toctree::
     :maxdepth: 1
 
-    platform_folder.rst
-    platform_ext_folder.rst
     porting_TFM_to_a_new_hardware
     documenting_platform.rst
-    platform_provisioning.rst
     platform_deprecation.rst
 
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-*Copyright (c) 2020, Arm Limited. All rights reserved.*
+*Copyright (c) 2020-2023, Arm Limited. All rights reserved.*