Some suggestions for the readme.

Currently, this is near the top:

The default committer is "GitHub Actions [email protected]", and the default author of the commit is "Your GitHub Username [email protected]".

Seems kinda weird to put that at the top. I recommend putting that info in the Usage section, since that's where all the other defaults are specified. Also I think the explanation of the defaults could be better.

How about something like this:

    # Optional commit user and author settings
    commit_user_name: Jane Smith # defaults to username of commit that triggered the run
    commit_user_email: [email protected] # defaults to email of commit that triggered the run
    commit_author: Jane Smith <[email protected]> # defaults to author of commit that triggered the run

Also, it seems like that maybe that's not currently how the default author settings work, but I think that's how they should work, so maybe I'll create a feature request for that.