Document JSON Schema team members list as markdown in the community repo

[Relequestual]

No description provided.

[jviotti]

Not something we have to do now, but it would be nice to start thinking about clearly documenting the process for somebody to become a member of JSON Schema. i.e. is a nominating + voting taking place, what is the minimum bar, etc?

[handrews]

And probably also a process for moving people to emeritus? Some of those folks are no longer active with the project. And for that matter, I don't know who some of them are at all.