Document GitHub API not returning private forks. Use GitHub App login

Created by: pjlast

It seems like the normal GitHub API, accessed with GitHub OAuth tokens, cannot return private repositories that are forks of other private repositories from the user's perspective (i.e. /user/repos will not contain the repo). @unknwon and @pjlast confirmed this in a call.

However, when a GitHub App login token is used, and GitHub App is installed authorized on that repository, then it is returned.

These a private forked repository seems to be quite rare