Bug 35865: Add missing hint about permissions when adding managers to a basket

Bug 35865: Add missing hint about permissions when adding managers to a basket

When searching for managers for an acquisition basket, the list of patrons is
limited to patrons with the baskets_managers permission. For other patron
searches there is a hint about the restriction but it does not appear here.

Test plan;
Edit a basket, click "Add user" to select a manager.
Notice the hint about the permission.

Signed-off-by: Loïc Vassaux--Artur <loic.vassaux-artur@outlook.fr>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>