Encourage good commit message etiquette

[oharrald-Dstl]

While easy enough to understand in context of its branch, a standalone commit message can be difficult to understand the meaning of when merged to the main branch. This isn't an essential, but it would be nice if we could encourage good Git commit message etiquette (see: https://blog.oddbit.com/post/2019-06-14-git-etiquette-commit-messages/) such that the reviewing of PRs, and tracing of commit history, becomes easier.

(Unless this is already encouraged somewhere, and I've yet to come across it... which is perhaps still reason to raise this issue?)