Add "Time unit format" section

[ydakuka]

This is easier to understand because when working with minutes, hours, etc., you need to explicitly specify the format.

[pirj]

I’ll close for now. Even though this might be easier to read, it’s unlikely to cause any other issues.

might be accepted in rails-stule-guide as a more generic guideline. They have “time arithmetic “ though, and I’m uncertain if 1.since(Time.current) even works, so most of this may be redundant.