Add API documentation

[emilydaemon]

from what I can tell, the API is not mentioned anywhere, not on the front page, not on the README.md, nothing
I've gotten an idea for a RiiTag homebrew app that could display your RiiTag without having to use the Internet Channel, but since there is no documentation, I have to look at the source code of this repository and RiiTag-RPC.
If nobody here's up to do it, and the API turns out to be simple enough for me to explain, I could probably try to write some.
Thank you!

[larsenv]

It would be nice if you could do it

[Brawl345]

The files in /src/pages/api are NOT the api you are looking for. It's a Next.js thing before they had the "app" folder. https://tag.rc24.xyz/api/user/USERID is the only public part. There was an attempt to make a real public API at #17 but I'm not developing RiiTag any further (and the file does not exist anymore, dunno why).

Do not ever use these "api" parts because they were not designed for that.

[GabubuAvailable]

It would be nice if you could do it

How could she do that if she doesn't even know how the system works?