Bug 12700 - Capitalization: "Close Help Window" in context help

Bug 12700 - Capitalization: "Close Help Window" in context help

To test:
- Open help in any page of staff client
- In help popup window, see wrong capitalization in button 'Close Help Window'
- Close the popup window
- Apply patch
- Check again: Button now reads "Close help window'

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Work as described, no koha-qa errors

Signed-off-by: Nick Clemens <nick@quecheelibrary.org>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>