Bug 29875: Update wording on maxreserves system preference

Bug 29875: Update wording on maxreserves system preference

To test:
1 - see the current wording
2 - apply patch
3 - words are changed

Test to confirm accuracy of wording:
1 - set maxreserves to 1
2 - set all/all circ rule to unlimited holds allowed total, holds allowed daily, and holds per record
3 - confirm you can place 1 hold for a patron, but the second is blocked
4 - set maxreserves to 0
5 - confirm you can place and number of holds for the patron
6 - set maxreserves to blank
7 - confirm you can place any number of holds for the patron

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>