Mention to send a patch before changing API or ABI.

Originally committed as revision 25373 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/developer.texi

@@ -149,9 +149,9 @@ should also be avoided if they don't make the code easier to understand.
    Also if you have doubts about splitting or not splitting, do not hesitate to
    ask/discuss it on the developer mailing list.
 @item
-   Do not change behavior of the program (renaming options etc) without
-   first discussing it on the ffmpeg-devel mailing list. Do not remove
-   functionality from the code. Just improve!
+   Do not change behavior of the program (renaming options etc) or public
+   API or ABI without first discussing it on the ffmpeg-devel mailing list.
+   Do not remove functionality from the code. Just improve!
 
    Note: Redundant code can be removed.
 @item