docs: update for autosquashing

docs/Brew-Test-Bot-For-Core-Contributors.md

@@ -11,8 +11,8 @@ If a pull request is correct and doesn't need any modifications to commit messag
     - Approving a PR for an existing formula will automatically publish the bottles and close the PR, taking care of this step.
 3. Watch the [actions queue](https://github.com/Homebrew/homebrew-core/actions) to ensure your job finishes. BrewTestBot will usually notify you of failures with a ping as well.
 
-If a pull request needs changes to the commit messages:
+If a pull request needs its commits squashed or its commit messages reformatted to [follow our style](https://docs.brew.sh/Formula-Cookbook#commit):
 
 1. Ensure the job has already completed successfully.
-2. Run `brew pr-pull 12345` where `12345` is the pull request number (or URL).
-3. Amend any relevant commits, then run `git push` to push the commits.
+2. Run `brew pr-pull --autosquash 12345` where `12345` is the pull request number (or URL). For revision bumps, rebuilds, and formula deletions, you can optionally include a `--message` argument to explain the change.
+3. Amend any relevant commits if needed, then run `git push` to push the commits.

docs/Homebrew-homebrew-core-Merge-Checklist.md

@@ -55,6 +55,7 @@ Check for:
   - formula `bottle :unneeded`, you can merge it through GitHub UI
   - bottles need to be pulled, and...
     - the commits are correct and don't need changes, approve the PR to trigger an automatic merge (use `brew pr-publish $PR_ID` to trigger manually in case of a new formula)
+    - the commits need to be squashed, use `brew pr-pull --autosquash $PR_ID` and `git push`
     - the commits need to be amended, use `brew pr-pull $PR_ID`, make changes, and `git push`
 - don't forget to thank the contributor
   - celebrate the first-time contributors