Doc: remove the todo plugin

Remove the sphinx todo plugin as managing a task list in the
documentation is confusing and inefficient.

Change-Id: I08912ac636c098865f187cef232cfb5f314a6d4d
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
diff --git a/docs/developer/writing-documentation.rst b/docs/developer/writing-documentation.rst
index eb10449..243dcec 100644
--- a/docs/developer/writing-documentation.rst
+++ b/docs/developer/writing-documentation.rst
@@ -40,14 +40,15 @@
 CMake
 '''''
 
-.. todo:: Add content about how to document cmake scripts.
-
+The project uses the ""`moderncmakedomain`_" Sphinx extension. This allows adding inline documentation to cmake files.
+For details please refer to the documentation of the plugin.
 
 --------------
 
 .. _`Restructured Text`: https://docutils.sourceforge.io/rst.html
 .. _`Sphinx`: https://www.sphinx-doc.org
+.. _`moderncmakedomain`: https://github.com/scikit-build/moderncmakedomain
 
-*Copyright (c) 2020-2021, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2020-2022, Arm Limited and Contributors. All rights reserved.*
 
 SPDX-License-Identifier: BSD-3-Clause