Documentation: Plan how moderation should work at scale

[rmccue]

@Ipstenu has been looking into this. We also have the moderation services from atproto where we can copy their design.

[Ipstenu]

See #12 for long discussions

[Ipstenu]

• https://github.com/bluesky-social/proposals/tree/main/0002-labeling-and-moderation-controls