[media] doc-rst: Add new types to media-types.rst

Changesets:
	eaa0b96b ("[media] media: Add video statistics computation functions")
and
	1179aab1 ("[media] media: Add video processing entity functions")

added some new elements to the "media entity types" table at the
DocBook. We need to do the same at the reST version, in order to
keep it in sync with the DocBook version.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>