Doc: Renamed links to "QML Applications".

"QML Application Developer Resources" is too long and the visible text
is usually shortened to "QML Applications".

The article in qt5/qtdoc changed title to "QML Applications".

Change-Id: I301f3b4659bd87631269b912bcc36f6f00fdeb2c
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>