Doc: Setting \qtvariable in module page.
Doc: Setting \qtvariable in module page.

\qtvariable indicates the QT variable needed in .pro files.

Change-Id: I3607f70e62436a56b746d1959c0175c636928903
Reviewed-by: Martin Smith <a8cc6484db2755056ccf1c457da8ca771f895dea@digia.com>
Reviewed-by: Alex Blasche <429ec4e831e8320529ddfedc4983cef56f3f7ae1@digia.com>

kobolabs/qtlocation,kobolabs/qtlocation,kobolabs/qtlocation