Bug 14056: Small punctuation error in description for deleting a holiday

Bug 14056: Small punctuation error in description for deleting a holiday

This patch just inserts a semi-colon into the description so that it makes more grammatical sense.

Test plan:
1) Go to Tools --> Calendar
2) Create or find a holiday, click on it so the editing options come up
3) Click on the question mark link to show the description for the option "Delete the exceptions on a range"
4) Confirm that this now has a semi-colon and reads "... Be careful about your scope range; if it is oversized you could slow down Koha."

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>