Bug 26299: Use same SMS number help text in OPAC as staff interface

Bug 26299: Use same SMS number help text in OPAC as staff interface

The SMS number help text in the OPAC follows a North American phone
number style. It should be more generic. To that end, this patch
makes the OPAC use the same help text for SMS numbers as
the staff interface

To test:
1) Apply the patch
2) Set "SMSSendDriver" to "Anything" in global system preferences
3) Go to the following link and note the help text by SMS number
http://localhost:8081/cgi-bin/koha/members/memberentry.pl?op=modify&destination=circ&borrowernumber=51
4) Go to http://localhost:8080/cgi-bin/koha/opac-messaging.pl
5) Note that the help text in both interfaces uses the same wording

Signed-off-by: Alexis Ripetti <alexis.ripetti@inLibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>