How to Write a Git Commit Message
chris.beams.io/posts/git-commit
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Fortunately, there are well-established conventions as to what makes an idiomatic git commit message. Indeed, many of them are assumed in the way certain git commands function. There's nothing you need to re-invent. Just follow the seven rules below and you're on your way to committing like a pro.