[TYPO3-doc] Encouraging people to contribute with Github

[Christian Müller]

Hi,

regarding review system there is much we oculd do with Github. We had a
nice chat with one of the Github guys as our codesprint lately and they
told us that there are possibilites for code reviews and hooking in.
Karsten and Robert know more.
Especially for documentation the workflow is of course awesome.

Cheers,
Christian