add link to go-github library
Merge pull request #257 from google/go-github

add link to go-github library
Clarify what /repositories does.
Merge pull request #258 from github/clarify-all-repositories

Clarify what /repositories does
Clarify how pagination works for /users.
Clarify how authentication works for /applications.
Merge pull request #260 from github/clarify-check-authorization-endpoint

Clarify how authentication works for /applications
Merge pull request #259 from github/clarify-users-endpoint

Clarify how pagination works for /users
Keep all support enquiries via GitHub contact page

Not sure if this is _really_ an issue however everywhere else directs users to
use the contact form on GitHub - just to keep consistency.
Merge pull request #261 from jacobbednarz/keep-support-enquiries-via-github

Keep all support enquiries via GitHub contact page
Send email subject in URL param for support links