Wholesome checker

This release builds on the previous one, checking the contents of the body and the diff, as well as the number of files and lines changed.

Initial

This is just a simple action that uses the GitHub API to check for stuff present in a PR. It's mostly an exercise of getting to know how it works, but can be useful to check that marks have been made on a PR body, or that you are changing a specific line or text in the code.