media: Documentation: Add a hyphen to list-based

Add a hyphen to list-based for uniform spelling in camera-sensor.rst.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>