media: Documentation: Align numbered list, make it a proper ReST

Align lines for numbered list so that Sphinx produces an uniform output
for all list entries. Also indent paragraphs of such list entries for
consistency.

Also use ReST numbered list syntax for the entries.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>