Update the porting documentation
Update the porting documentation

- Remove some references to the legacy imports
- Mention the biggest change, separate QML types
- Add some examples on what changed in the QML API

Change-Id: Icdbf8271935499ec449a35919d947ad762d2cf03
Reviewed-by: Bernd Weimer <25a3520e34823a8a61fd4930799b4649e70db8bb@rim.com>
Reviewed-by: Lorn Potter <0e329dfd61bdd4e2b2b708a31f12f199a7656feb@jollamobile.com>

richardmg/qtsensors,mer-qt/qtsensors,kobolabs/qtsensors,richardmg/qtsensors,mer-qt/qtsensors,richardmg/qtsensors,richardmg/qtsensors,kobolabs/qtsensors,richardmg/qtsensors,mer-qt/qtsensors,kobolabs/qtsensors,mer-qt/qtsensors,kobolabs/qtsensors,mer-qt/qtsensors