Doc: Update QML Getting Started tutorial

This change addresses issues with the QML getting started
tutorial:
    - Fix and clean up code snippets
    - Update to discuss QML modules
    - Fix linking, language issues and typos

Change-Id: Idb8bc6be9b1dd5b302bea3eb78154553b10b66df
Reviewed-by: Venugopal Shivashankar <venugopal.shivashankar@digia.com>
Reviewed-by: Alan Alpert <aalpert@blackberry.com>