docs: consolidate code review process documentation

From the page listing the maintainers and code owners [1], add a link
to the code review guidelines page [2], which in turn has a link to
the tf.org code review process [3].

Before that patch, both pages [1] and [2] had a link to
[3]. Hopefully, this change will guide the reader better so they don't
miss out on any information.

Additionally, move some of the information from the top of page [1]
into page [2] and add extra details about the code review process used
in TF-A and how that get translated in Gerrit.

[1] https://trustedfirmware-a.readthedocs.io/en/latest/about/maintainers.html
[2] https://trustedfirmware-a.readthedocs.io/en/latest/process/code-review-guidelines.html
[3] https://developer.trustedfirmware.org/w/collaboration/project-maintenance-process/



Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Change-Id: I56562a72443f03fff16077dadc411ef4ee78666d

docs/about/maintainers.rst

@@ -2,12 +2,11 @@ Project Maintenance
 ===================
 
 Trusted Firmware-A (TF-A) is an open governance community project. All
-contributions are ultimately merged by the maintainers listed below. Technical
-ownership of most parts of the codebase falls on the code owners listed
-below. An acknowledgement from these code owners is required before the
-maintainers merge a contribution.
+contributions are reviewed and merged by the community members listed below.
 
-More details may be found in the `Project Maintenance Process`_ document.
+For more details on the roles of `maintainers`, `code owners` and general
+information about code reviews in TF-A project, please refer to the :ref:`Code
+Review Guidelines`.
 
 .. |M| replace:: **Mail**
 .. |G| replace:: **GitHub ID**
@@ -980,5 +979,3 @@ Conventional Changelog Extensions
 .. _bytefire: https://github.com/bytefire
 .. _rupsin01: https://github.com/rupsin01
 .. _jimmy-brisson: https://github.com/theotherjimmy
-
-.. _Project Maintenance Process: https://developer.trustedfirmware.org/w/collaboration/project-maintenance-process/

docs/process/code-review-guidelines.rst

 Code Review Guidelines
 ======================
 
-This document provides TF-A specific details about the project's code review
-process. It should be read in conjunction with the `Project Maintenance
-Process`_, which it supplements.
-
-
 Why do we do code reviews?
 --------------------------
 
@@ -23,8 +18,34 @@ Code reviews are meant to benefit everyone through team work. It is not about
 unfairly criticizing or belittling the work of any contributor.
 
 
-Good practices
---------------
+Overview of the code review process
+-----------------------------------
+
+All contributions to Trusted Firmware-A project are reviewed by the community to
+ensure they meet the project's expectations before they get merged, according to
+the `Project Maintenance Process`_ defined for all `Trusted Firmware` projects.
+
+Technical ownership of most parts of the codebase falls on the :ref:`code
+owners`. All patches are ultimately merged by the :ref:`maintainers`.
+
+Approval of a patch is tracked using Gerrit `labels`. For a patch to be merged,
+it must get all of the following votes:
+
+- At least one ``Code-Owner-Review+1`` up-vote, and no ``Code-Owner-Review-1``
+  down-vote.
+
+- At least one ``Maintainer-Review+1`` up-vote, and no ``Maintainer-Review-1``
+  down-vote.
+
+- ``Verified+1`` vote applied by the automated Continuous Integration (CI)
+  system.
+
+Note that, in some instances, the maintainers might give a waiver for some of
+the CI failures and manually override the ``Verified+1`` score.
+
+
+Good practices for all reviewers
+--------------------------------
 
 To ensure the code review gives the greatest possible benefit, participants in
 the project should:
@@ -211,6 +232,6 @@ concerns, questions, or any other type of blocking comment, they should set
 
 --------------
 
-*Copyright (c) 2020, Arm Limited. All rights reserved.*
+*Copyright (c) 2020-2023, Arm Limited. All rights reserved.*
 
 .. _Project Maintenance Process: https://developer.trustedfirmware.org/w/collaboration/project-maintenance-process/