Doc: Expand example (importing multiple modules into 1 namespace)

Snippet is for the Qt QML "Import Statements" page. Show how to use the
namespace to reference types from different modules

Change-Id: I8c49703194a18657439afdef75e47ff7e97be653
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Alan Alpert <aalpert@blackberry.com>