fixup! [llvm][docs][nfc] Add a note on GitHub's "squash and merge"

Expand as per David's suggestions

Author: banach-space

llvm/docs/Contributing.rst

@@ -129,16 +129,10 @@ review by 'ping'ing the GitHub PR with "Ping" in a comment. The common courtesy
 is once a week. Please remember that you are asking for valuable time from
 other professional developers.
 
-After your PR is approved, ensure that:
-
-  * The PR title and description describe the final changes. These will be used
-    as the title and message of the final squashed commit. The titles and
-    messages of commits in the PR will **not** be used.
-  * You have set a valid email address in your GitHub account, see :ref:`github-email-address`.
-
-Now you can merge your PR. If you do not have the ability to merge the PR, ask your
-reviewers to merge it on your behalf. You must do this explicitly, as reviewers'
-default assumption is that you are able to merge your own PR.
+After your PR is approved, you can merge it. If you do not have the ability to
+merge the PR, ask your reviewers to merge it on your behalf. You must do this
+explicitly, as reviewers' default assumption is that you are able to merge your
+own PR.
 
 For more information on LLVM's code-review process, please see
 :doc:`CodeReview`.
@@ -148,6 +142,10 @@ For more information on LLVM's code-review process, please see
 For developers to commit changes from Git
 -----------------------------------------
 
+.. note::
+   See also :doc:`landing-your-change` for more details on merging your changes
+   into LLVM project monorepo.
+
 Once a patch is reviewed, you can select the "Squash and merge" button in the
 GitHub web interface.
 

llvm/docs/GitHub.rst

@@ -15,6 +15,12 @@ The LLVM Project uses `GitHub <https://github.com/>`_ for
 This page describes how the LLVM Project users and developers can
 participate in the project using GitHub.
 
+Before your first PR
+====================
+
+Please ensure that you have set a valid email address in your GitHub account,
+see :ref:`github-email-address`.
+
 Branches
 ========
 
@@ -144,6 +150,7 @@ Approvals
 Before merging a PR you must have the required approvals. See
 :ref:`lgtm_how_a_patch_is_accepted` for more details.
 
+.. _landing-your-change:
 Landing your change
 -------------------
 
@@ -215,12 +222,19 @@ commonly used first:
   this result correctly with a note that a force push did occur.
 
 .. note::
-   When using `Squash and merge` in LLVM’s GitHub web interface, GitHub will
-   use the pull request title and description as the commit message. Only
-   users with commit access can edit the commit message just before merging a PR.
+   The LLVM Project monorepo on GitHub is configured to always use "Squash
+   and Merge" as the pull request merge option when using the web interface.
+   With this option, GitHub uses the PR summary as the default commit
+   message.
+
+   Users with commit access who can merge PRs have a final opportunity to edit
+   the commit title and message before merging. However, this option is not
+   available to contributors without write access.
 
-   If you do not have write permissions, make sure the PR title and description
-   are **up to date** before the review process concludes.
+   In practice, PR summaries often become commit messages. Ensure that the PR
+   title and description are up to date, free of typos, and clearly written —
+   especially if you do not have write permissions and require someone else to
+   merge your PR.
 
 Pre-merge Continuous Integration (CI)
 -------------------------------------
@@ -445,8 +459,8 @@ Releases
 Backporting Fixes to the Release Branches
 -----------------------------------------
 You can use special comments on issues or pull requests to make backport
-requests for the release branches.  To do this, after your pull request has been
-merged:
+requests for the release branches.  To do this, after your pull request has
+been merged:
 
 1. Edit "Milestone" at the right side of the isssue or pull request
    to say "LLVM X.Y Release"