Staff should be exempt from user mention limit

[Stefan_Fairphone (Stefan Brand)]

@sam

Is there a reason group mentions are not being used here, seems like a better fit.

I would need at least 3 groups then:

@going_to_amsterdam_but_doesnt_need_accomodation
@unsure_whether_going_to_amsterdam
@going_to_amsterdam_and_needs_accomodation

Plus: As @jomaxro says, I’d need to ask my admin to create these groups (and to add users, if I get new info from people).

PS.: There is another argument: The information, who is going, and who is not, is only relevant for the people, who have been added to the PM. A group on the other hand is public (and, btw., creates far too much overhead for the simple task of listing multiple user names).