release_notes: mention more codecs

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/RELEASE_NOTES

@@ -9,7 +9,8 @@ General notes
 -------------
 
 This release enables frame-based multithreaded decoding for a number of codecs,
-including VP8, H.263 and H.264. Additionally, there has been a major cleanup of
+including theora, huffyuv, VP8, H.263, mpeg4 and H.264. Additionally, there has
+been a major cleanup of
 both internal and external APIs. For this reason, the major versions of all
 libraries have been bumped. On the one hand, this means that 0.7 can be installed
 side-by-side with previous releases, on the other hand, in order to benefit