Bug 27026: (bug 24159 follow-up) Add a tooltip to explain the values of "Days mode"

Bug 27026: (bug 24159 follow-up) Add a tooltip to explain the values of "Days mode"

There was a tooltip for values of the existing rules, but not the only
you were editing.

Now there is the same tooltip (title) on the option elements of the
dropdown list.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Bug 27026: Use meaningful descriptions

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>