Doc: Updated the list of Demos published

Added a couple of links to apps that are published on Android
and iOS app stores.

Change-Id: Ied6c3723d7b38b722a7ac5c9865f4d7eeaef87da
Reviewed-by: Nico Vertriest <nico.vertriest@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>