Chapter 1 : Update "contao-check.jpg"
Use example domain name (RFC2606).
Use the same example domain as English vresion.
Do not use "www.domain.com" but "www.example.com".
The previous name is restored
Add "Benutzer-Authentifizierung und Rechteprüfung"
Fix the user import example
Fix the annotated issues
Renamed file to follow naming conventions
Merge branch 'feature/benutzer-authentifizierung' into 2.11
Merge branch '2.11' into 3.0
Merge branch '3.0' into 3.1
Merge branch '3.1' into 3.2
Merge branch 'update-img-contao-check' of https://github.com/lionel-m/docs into 3.1
Merge branch '3.1' into 3.2
Merge branch '2.11-fix-example-domain' of https://github.com/taca/docs into 2.11
Merge branch '2.11' into 3.0
Merge branch '3.0' into 3.1
Merge branch '3.1' into 3.2
Update 07-Customizing-Contao.md

Updated the manual for Contao 3