Document how to utilize Github API with Github login

After some adjustments Marc made to the Github Oauth Login, it's now possible to make full use of the Github API for IHP Pro apps. It's now only missing some documentation.

Todo

• How to get accessToken as implicit parameter from user oauth session
• How to override scope for Github Oauth apps (default is user:email which is the bare minimum for getting Oauth app working)
• Example of how to write an http request to Github API with Wreq fetching Github user data