Follow the conventions at
http://qt-project.org/wiki/Spelling_Module_Names_in_Qt_Documentation



QtMultimedia -> Qt Multimedia

(Also, QtMultimediaKit has been merged into Qt Multimedia in Qt 5)

Change-Id: I3c23435d5eceb946ea320756b835da937726db24
Reviewed-by: Laszlo Papp <lpapp@kde.org>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>