[llvm] [llvm][docs] Reorder Stacked PR approaches in GitHub.rst (PR #138126)

[Andrzej Warzyński via llvm-commits]

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@@ -274,8 +264,25 @@ Your options are as follows:
 
    This approach allows GitHub to display clean, incremental diffs for each PR
    in the stack, making it much easier for reviewers to see what has changed at
-   each step. Once `feature_1` is merged, you can rebase and re-target
-   `feature_2` to `main`.
+   each step. Once `feature_1` is merged, GitHub would automatically rebase and
+   re-target your branch `feature_2` to `main`. For more complex stacks, you can
+   perform this step using the web interface.
+
+   This approach requires
+   `Commit Access <https://llvm.org/docs/DeveloperPolicy.html#obtaining-commit-access>`_
+   . However, if you are involved with a Stacked PR, there's a good chance you'll
+   be granted access.
+
+#. Two PRs with a dependency note
+
+   Create PR_1 for `feature_1` and PR_2 for `feature_2`. In PR_2, include a
+   note in the PR summary indicating that it depends on PR_1 (e.g.,
+   “Depends on #PR_1”).
+
+   The disadvantage of this approach is that GitHub will not show a clean diff.
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banach-space wrote:

Note the `note` below:
>    When not using user branches, GitHub will not display proper diffs for
   subsequent PRs in a stack. Instead, it will show a combined diff that
   includes all commits from earlier PRs

https://github.com/llvm/llvm-project/pull/138126