[WIP] Federation infographic, or "federation for dummies".

This infographic is still incomplete; I'm posting it here in the hope that I can get some feedback about it. It has three goals:

1. To explain what federation is. No technobabble, just a simple analogy with houses and a neighbourhood.
2. To explain why federation is good for users.
3. [TODO] Specific info about the Fediverse, plus some really simple FAQ.

Criticism is welcome as long as constructive.

EDIT: OK, too much text. I'm clipping as much as I can.