Bug - 11345 - Self registration captcha

Bug - 11345 - Self registration captcha

Test Plan
 - Open the opac site
 - Navigate to the self registration page (Home -> Register here)
 - Notice that there is no note stating that the verification box is case-sensitive
 - Apply patch
 - Refresh page
 - Notice that there is now an extra note stating that the verification box is case-sensitive.

Followed test plan. Hint displays as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Mason James <mtj@kohaaloha.com>