[BUGFIX] fixes wrong git repository url in documentation

Change-Id: I7794b97ce20baa51e56623fa44a663c15b71758c
Resolves: #59119
Reviewed-on: https://review.typo3.org/30395
Reviewed-by: Peter Kraume
Tested-by: Peter Kraume
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer