Bug 8918: (follow-up) improve descriptions of two related sysprefs

Bug 8918: (follow-up) improve descriptions of two related sysprefs

Updating pref descriptions for ReservesNeedReturns and ILS-DI:AuthorizedIPs.
Just sideway related to this report, but not important enough to separate.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 5372082724002476bc7565f7c66a7e6aaa06c24b)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>