WelcomeScreen: Changing the "Getting Started Now" button url

We want to reduce the needed number of clicks to the Android setup
info from 4 to 2 clicks. Therefore the main index.html is better.
Also that page does not open in split help, anymore.

Change-Id: Idfd08c78728cb2face6cf9769ca332ac8805eef5
Reviewed-by: Sami Makkonen <sami.makkonen@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>