Encourage clean commit messages

I think Derek can help us with commit messages - as a sort of "linter"

Some may argue a pre-commit hook could do this, but it would have to live in every git repo - Derek can automate some of this.

This post by Chris Beans seems to be well-regarded in the larger community and is also referenced vey the Moby project: https://chris.beams.io/posts/git-commit/

* Always start a commit subject (first line) with a capital letter
* Never exceed 50 chars for the first line of a commit message
* When a commit body is given make sure it wraps to 70 chars max per line

This would be a "feature" and it would be up to the project maintainers as to what they do with the information.

If the rules are invalidated a label could be added with a comment. When the rules are valid the label will be removed. You could get the label more than once but not whilst the "label" is still in place.

Label could be: `review/commit-msg`