Bug 25045: (follow-up) Add a note to OpacPublic

Bug 25045: (follow-up) Add a note to OpacPublic

This patch tweaks the OpacPublic system preference description so users
don't expect, incorrectly, this syspref to disable the public API
anonymous access.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 3d3a07c5ee0098c3fe504009144b5c0545c0e75f)

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>