Distinction between reservable with and without superivision

[EwoutV]

We want to enable locations to work with reservable timeslots even if they don't want to check reservations when students come in. The reservations can still be used as an indictation for students on how full a location is for a certain day. This also enables more complete statistics.

This is already possible, but should be made more clear for admins. E.g. a message "This location works with reservations, as an indication of the occupation grade for students and more complete occupation statistics".