docs: Update migration doc (backport #18288)

[mergify]

---

This is an automatic backport of pull request #18288 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 283215a has failed:

On branch mergify/bp/release/stable/5.4/pr-18288
Your branch is ahead of 'origin/release/stable/5.4' by 14 commits.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 283215aab8.
  (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 modified:   doc/import_external_docs.ps1

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

Cherry-pick of 53b792e has failed:

On branch mergify/bp/release/stable/5.4/pr-18288
Your branch is ahead of 'origin/release/stable/5.4' by 15 commits.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 53b792eb9c.
  (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 modified:   doc/import_external_docs.ps1

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

Cherry-pick of 510546b has failed:

On branch mergify/bp/release/stable/5.4/pr-18288
Your branch is ahead of 'origin/release/stable/5.4' by 16 commits.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 510546bd74.
  (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 modified:   doc/import_external_docs.ps1

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