Add APIchanges entry for the AVFilterBufferRef changes in r24773.

Originally committed as revision 24774 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/APIchanges

@@ -13,6 +13,11 @@ libavutil:   2009-03-08
 
 API changes, most recent first:
 
+2010-08-11 - r24773 - lavfi 1.34.0 - AVFilterBufferRef
+  Resize data and linesize arrays in AVFilterBufferRef to 8.
+
+  This change breaks libavfilter API/ABI.
+
 2010-08-11 - r24768 - lavc 52.85.0 - av_picture_data_copy()
   Add av_picture_data_copy in avcodec.h.