[8.x](backport #4632) docs: fix Dockerfile.build name

[mergify]

---

This is an automatic backport of pull request #4632 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of a0057cc has failed:

On branch mergify/bp/8.x/pr-4632
Your branch is up to date with 'origin/8.x'.

You are currently cherry-picking commit a0057cc.
  (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/rm <file>..." as appropriate to mark resolution)
	deleted by us:   docs/docker-images.md

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

[andrzej-stencel]

Irrelevant for this branch.