Improve UI of enabling nagging mode

Currently there is only a toggle and it is not quite clear what it does until you click on it.

[felixwiemuth]

The nagging toggle is already planned to be replaced by a reminder-type selection menu, because there will be more reminder types :).

Okay should this issue be closed as a duplicate?

[felixwiemuth]

No it's okay to stay open, for reference until it's done