Add Advancement API guide to wiki

[Fyorl]

Originally in GitLab by @Fyorl

[Fyorl]

Originally in GitLab by @arbron

Is this a plan to start making use of the wiki here on GitLab?

[Fyorl]

Originally in GitLab by @Fyorl

Yeah, I think so. I think we discussed something like this back when we did the initial planning but the details are a bit fuzzy. I think an API guide would be useful, and the wiki seems like the best place for it from what I can tell.

[Fyorl]

Originally in GitLab by @arbron

Okay, I've begun work on an advancement page for the wiki.

Unfortunately GitLab wikis don't support Merge Requests, so I wasn't able to do the work on my own fork.

[Fyorl]

Originally in GitLab by @Fyorl

Thanks Jeff, I was planning on doing it myself today but adding extra typing to scale values just sucked up the entire day. You are probably best placed to write about the API anyway, I think you can feel free to edit the wiki as you please.

[Fyorl]

Originally in GitLab by @akrigline

I'm not 100% about this, worth testing to be sure, but I think if a module registers an advancement during init it will have done so after the system's init and thus too late for item preparation?

[Fyorl]

Originally in GitLab by @arbron

In my testing item preparation didn't occur until after the "setup" hook was called.

[Fyorl]

Originally in GitLab by @akrigline

gotchya, perfect!