[8.x] 8.18: update docs (backport #15470)

[mergify]

Merge as soon as branch is created and the GitHub checks are green. And the PR in main for the Mergify changes has been merged.

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This is an automatic backport of pull request #15470 done by Mergify.

[mergify]

Cherry-pick of 711b3e6 has failed:

On branch mergify/bp/8.x/pr-15470
Your branch is up to date with 'origin/8.x'.

You are currently cherry-picking commit 711b3e6f.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both added:      changelogs/8.18.asciidoc

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

This pull request has not been merged yet. Could you please review and merge it @? 🙏