Doc: import statements go to QML files, not pro files

Change-Id: Ia36ffd51add0c92b396e448d8e125848e9754877
Reviewed-by: Venugopal Shivashankar <venugopal.shivashankar@digia.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>