Tooltip in registration form for Debitorennummer

[LukasGibeh]

The past has shown has new members are sometimes struggling to find the "Debitorennummer" that is required upon registration.

In order to make the registration process more convenient, team BuS proposes to add some help (e.g. as a tooltip) close to the respective text field. One idea would be to show Studentenwerk's example Mietvertrag and highlight the position of the Debitorennummer.