Add README with basic documentation?

[nickrobinson251]

This could clarify both

• what the General registry is, how one is expected to interact with it as a package developer (i.e. Registrator, optionally TagBot, but also you can make PRs to edit files directly)
• how to do a few things beyond tagging a new release e.g. how do I rename a package? How do I "blacklist" a version?

[nickrobinson251]

could also point to https://julialang.github.io/Pkg.jl/v1/registries/

and maybe the things mention in the second bullet point above actually belong on that page?

[StefanKarpinski]

Sure, seems like a good idea.

[ericphanson]

I made a PR with some basic docs here: #3567. I was more focused on giving explanations for common “waiting for author” holds, from what I’ve seen looking at registrator PRs, than blacklisting and things like that though (which I don’t actually know how to do).

[DilumAluthge]

Can we add a link in the README to https://github.com/JuliaRegistries/RegistryCI.jl? And maybe we can have a note saying that to report issues with automerge, please open an issue in the RegistryCI.jl repo (not the General registry repo)?

[DilumAluthge]

Fixed by #6335.

Of course, we can (and should) continue to expand and improve the README, see e.g. #3567