[media] video.rst: a sensor is also considered to be a physical input

Add the line "Camera sensors are also considered to be a video input."

In practice all non-MC drivers for sensors support the input ioctls, and the
compliance test actually tests for the presence of these ioctls. So clarify
the documentation by explicitly mentioning sensors.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/v4l/video.rst

@@ -8,9 +8,10 @@ Video Inputs and Outputs
 
 Video inputs and outputs are physical connectors of a device. These can
 be for example RF connectors (antenna/cable), CVBS a.k.a. Composite
-Video, S-Video or RGB connectors. Video and VBI capture devices have
-inputs. Video and VBI output devices have outputs, at least one each.
-Radio devices have no video inputs or outputs.
+Video, S-Video and RGB connectors. Camera sensors are also considered to
+be a video input. Video and VBI capture devices have inputs. Video and
+VBI output devices have outputs, at least one each. Radio devices have
+no video inputs or outputs.
 
 To learn about the number and attributes of the available inputs and
 outputs applications can enumerate them with the