V4L/DVB (9369): Documentation update for cx88

Attached is a patch that updates the cx88 documentation to add the fact the
closed caption works for at least NTSC capture.

ps: I also updated the wiki at:
http://www.linuxtv.org/v4lwiki/index.php/Text_capture#cx88_devices

Signed-off-by: Rafael Diniz <diniz@wimobilis.com.br>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/video4linux/README.cx88

@@ -27,8 +27,8 @@ audio
 	  sound card) should be possible, but there is no code yet ...
 
 vbi
-	- some code present.  Doesn't crash any more, but also doesn't
-	  work yet ...
+	- Code present. Works for NTSC closed caption. PAL and other
+	  TV norms may or may not work.
 
 
 how to add support for new cards