Document oauth callback urls & app settings in general

[colinscape]

What's not great

Would be great to have some information on where this information is and how to get to it. Eg for Twitter, Facebook, and all the networks we support, they often have a bunch of settings that may or may not be relevant but can be useful & important in some circumstances.

Also, not just where it is and how to get to it, but who has access, since not everyone has access to all the various apps across all the networks.

Why this is confusing

Not confusing, just missing.

(Bonus!) What would be better?