Added "textblock" value to requireCapitalizedComments

This makes the most sense to me right now. If you're good with this implementation then I'll add the docs to this PR as well. Fixes #767.
Just an fyi, we typically don't include the name of the committer in the code; that info could be found via `git blame`. I'll remove post-merge.

It's also pretty clear that the helper cleans things up a bit.