That's great, that should be shown to all "how can you dare ask for docs when you have man pages".
Although the point of RTFM is very legitimate, man pages are often well complimented by tutorials, cheatsheets and everything that can help someone be productive.
master and origin are mere conventions, you can call your upstream remote and upstream branch whatever you want, although it's good to respect convetions. I make this comment because the guide does not make note of this fact.
https://git-man-page-generator.lokaltog.net/
(to be clear, this will randomly generate a nonsense fake git man page, but it's hard to distinguish from the real documentation)