Update en-GB.com_users.ini

Same as master / staging see:
https://github.com/joomla/joomla-cms/commit/7b6ff99d26048e3c0e3a2cc1c66c49a0d6d3a7b1
Merge pull request #2705 from zero-24/patch-5

$ Correcting typo in language string [2.5.x]