Doc: Add documentation for the deployment of the Controls

Document the fact that Qt Quick Controls javascript and qml files are
embedded in resources. This is useful while deploying the controls while
it has some limitations.

Change-Id: Ie6cf34e644fc4542742080d38643015a3d3fe0bd
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>