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/design_docs/hardware_abstraction_layer.rst b/docs/design_docs/hardware_abstraction_layer.rst
index 89b7092..2a06297 100644
--- a/docs/design_docs/hardware_abstraction_layer.rst
+++ b/docs/design_docs/hardware_abstraction_layer.rst
@@ -71,8 +71,8 @@
     permitted access to those assets. Currently, :term:`TF-M` only needs the
     debug authentication. The whole debug mechanism and related :term:`HAL` will
     be enhanced in the future. Please refer to the :doc:`Debug authentication
-    settings section </integration_guide/platform/platform_folder>` for more
-    details.
+    settings section </integration_guide/source_structure/platform_folder>`
+    for more details.
 
 *****************
 Design Principles
diff --git a/docs/design_docs/source_structure.rst b/docs/design_docs/source_structure.rst
deleted file mode 100644
index 89d7205..0000000
--- a/docs/design_docs/source_structure.rst
+++ /dev/null
@@ -1,164 +0,0 @@
-###################################
-Trusted Firmware-M Source Structure
-###################################
-
-:Organization: Arm Limited
-:Contact: tf-m@lists.trustedfirmware.org
-
-.. note::
-  Reference the document :doc:`Glossary </glossary>` for terms
-  and abbreviations.
-
-************
-Introduction
-************
-TF-M is designed to provide a user-friendly source structure to ease
-integration and service development. This document introduces the source
-structure and its design intention of TF-M.
-
-.. note::
-  - This document goes ahead of the implementation so the existing source
-    structure may be different from the description listed here. It is
-    recommended to refer to this document for ongoing code structure changes.
-  - By getting feedback from the practical implementation, this document is
-    updated continuously before it is detailed enough to be a user guide.
-
-****************
-Source Structure
-****************
-The description of the source structure is broken down into subsections, each
-subsection introduces one detailed folder.
-
-Root Directory
-==============
-This table describes the structure under the root directory with part of
-possible folders. Note that the ``Detailed`` field indicates if the folder is
-described in details here in this document:
-
-============= ==================================== ====================
-Folder name   Purpose                              Detailed
-============= ==================================== ====================
-bl2           The 2nd stage bootloader.            No.
-cmake         Cmake files.                         No.
-configs       Configuration system files.          No.
-docs          The documentations.                  No.
-lib           The 3rd party library.               No.
-**platform**  Platform intermedia files.           See `'platform'`_.
-**secure_fw** The secure firmware.                 See `'secure_fw'`_.
-tools         Tools in scripts for building.       No.
-============= ==================================== ====================
-
-'platform'
-==========
-The platform sources contain necessary platform sources or intermedia files
-pointing to the sources out of TF-M folder.
-
-========================= =============================================
-Folder name               Purpose
-========================= =============================================
-common/\*                 Common HAL implementation.
-include/\*                Platform public headers.
-<vendor>                  Vendor specific folders.
-========================= =============================================
-
-.. note::
-  The ``common`` folder contains the example implementation of the ``HAL`` API
-  bases on common ``system`` (CMSIS e.g.). The platform could reference to
-  sources in the ``common`` folder directly if applicable or apply a
-  customized HAL implementation.
-  A ``system`` can have a standalone folder under ``common``, depends on how
-  'common' this system is. Each ``platform vendor`` is assigned with one
-  folder for usage. As the content of the ``vendor`` folder comes by the
-  contribution of vendors, the ``vendor`` manages the structure inside it.
-
-'secure_fw'
-===========
-This folder contains components needed by secure firmware, and the exported
-interfaces for application, service development and HAL integration:
-
-================= ===================================== ======================
-Folder name       Purpose                               Detailed
-================= ===================================== ======================
-**include**       Public headers of 'secure_fw'.        See `'include'`_
-**partitions**    Default services and supportings.     See `'partitions'`_
-**spm**           PSA-FF-M SPM implementation. [1]      See `'spm'`_
-================= ===================================== ======================
-
-.. note::
-  1. A PSA-FF-M complied SPM implementation.
-
-  The headers referenced by other modules are public headers and put under the
-  'include' folder of the current module. Do not put headers not referenced by
-  other modules in this 'include' folder.
-
-'include'
----------
-This folder holds headers for client, services and platform integration usage.
-
-=========================== ===================================================
-Folder name                 Purpose
-=========================== ===================================================
-psa/\*                      PSA FF Client API.
-=========================== ===================================================
-
-.. note::
-  TFM applies an explicit including policy. Each module's headers are put into
-  a specific folder which follows the pattern '\*/inc', this folder needs to be
-  added into the project's searching path if this project needs to include
-  headers in this folder. The 'inc' in a path indicates the end of
-  including-path. If there are subfolders under folder 'inc', apply a
-  hierarchy including.
-
-'partitions'
-------------
-This folder contains default services implemented as partitions and necessary
-partition runtime utilities provided by TF-M.
-
-================================= =============================================
-Folder name                       Purpose
-================================= =============================================
-lib/runtime/\*                    The SPRTL sources and intermedia files. [1]
-lib/runtime/shared\*              Sources can be shared by out of SPRTL. [2]
-<partition_x>/\*                  Files for 'partition_x'.
-<partition_x>/include/\*          RoT Service API headers of 'partition_x'. [3]
-<partition_y>/\*                  Files for 'partition_y'.
-<partition_y>/include/\*          RoT Service API headers of 'partition_y'. [3]
-================================= =============================================
-
-.. note::
-  1. The SPRTL sources and intermediate files. SPRTL contains sources from
-     other folders, such as necessary RoT Service API implementation from
-     'partitions' folder.
-  2. The sources here can be referenced by the building system out of SPRTL.
-     Generally, they are runtime and PSA APIs.
-  3. Here takes 'partition_x' and 'partition_y' as an example, and showcases
-     a detailed structure of them. The `<interface>` contains the RoT Service
-     API for client calls.  The folder name of this client-orient folder is
-     decided by the service developer.
-
-'spm'
------
-The SPM is the core component to provide a mechanism for providing secure
-services.
-
-=================================== ===========================================
-Folder name                         Purpose
-=================================== ===========================================
-include/\*                          SPM public headers.
-ffm/\*                              SPM logic complies with PSA-FF-M and
-                                    its necessary supporting functionalities,
-                                    such as the runtime API and the thread
-                                    operation, etc.
-cmsis_psa/\*                        CMSIS implementation for PSA-FF-M SPM. [1]
-\*                                  Implementation sources.
-=================================== ===========================================
-
-.. note::
-  1. CMSIS is the first implementation system.
-  2. This folder contains a function call based secure firmware implementation.
-     This model is the prototype model which would be updated after the PSA
-     model. Create a standalone folder to hold it.
-
---------------
-
-*Copyright (c) 2020-2022, Arm Limited. All rights reserved.*