MAINTAINERS: Update media entries

Now that we've created a /drivers/staging/media, put it together with
/drivers/media. Also, added there a missing entry for the Media API spec.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

MAINTAINERS

@@ -4234,7 +4234,9 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6.git
 S:	Maintained
 F:	Documentation/dvb/
 F:	Documentation/video4linux/
+F:	Documentation/DocBook/media/
 F:	drivers/media/
+F:	drivers/staging/media/
 F:	include/media/
 F:	include/linux/dvb/
 F:	include/linux/videodev*.h