Comment by dpifke

The official documentation contains some guidelines and the reasoning behind them:

https://git-scm.com/book/ms/v2/Distributed-Git-Contributing-...

https://git-scm.com/docs/SubmittingPatches#describe-changes

For examples of projects that do this very well, I usually point people to the Linux kernel (for which Git was invented) and Go.

https://www.kernel.org/doc/html/latest/process/submitting-pa...

https://go.dev/doc/contribute#commit_messages