[Doc] create github project  #12

You need a documentation for adding a github repostory.
For me i needed to do :

• set github key in app/config.yml (when adding projet, it will list project in php-censor)
• install the deploy key into the github project
• create a new github projet
• select github type
• wait & select from the list the right project

if key error => deploy key not installed

the error message during the creation are not in a visible color (like red), not very visible