media: uvcvideo: document UVC v1.5 ROI

Added documentation of V4L2_CID_UVC_REGION_OF_INTEREST_RECT and
V4L2_CID_UVC_REGION_OF_INTEREST_AUTO.

An example of a userspace implementing this feature can be found at:
https://chromium.googlesource.com/chromiumos/platform2/+/refs/heads/release-R121-15699.B/camera/hal/usb/



Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Yunke Cao <yunkec@google.com>
Tested-by: Yunke Cao <yunkec@google.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Link: https://lore.kernel.org/r/20250203-uvc-roi-v17-17-5900a9fed613@chromium.org


Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>