media: Documentation:media:v4l-drivers: Update vivid documentation.

Add metadata capture/output and v4l-touch support in vivid
documentation.

Signed-off-by: Vandana BN <bnvandana@gmail.com>
[hverkuil-cisco@xs4all.nl: fixed some typos, made some small tweaks of the text]
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>