Sensors support WinRT since Qt 5.3

Make it obvious in the module overview.

Change-Id: I0e8bc72d098111f841e4aa50842c5102c4949bd4
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>