Doc: Add images to QtWinExtras examples

Link images of examples already used in the overview page
to the example docs as well, and add a new image for the
jumplist example.

Change-Id: I09c00cff0bf4b0874f7f80eee93ce9e6d3842507
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>