media: Documentation:media:v4l2:Add vivid metadata doc

Adds new file for describing new metadata format V4L2_META_FMT_VIVID added in vivid driver.

Signed-off-by: Vandana BN <bnvandana@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>