The extension Cite is distributed with MediaWiki 1.21 (released May 2013) and is integrated in core since MediaWiki 1.25. No need to keep that notice any longer.

Change-Id: I8a91fbb45bc6f410b551c206177d63c584349c37
Reviewed-on: https://gerrit.libreoffice.org/51795Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
Tested-by: Olivier Hallot <olivier.hallot@libreoffice.org>