doc: fix API examples references.

doc/developer.texi

@@ -14,12 +14,13 @@
 @section API
 @itemize @bullet
 @item libavcodec is the library containing the codecs (both encoding and
-decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
+decoding). Look at @file{doc/examples/decoding_encoding.c} to see how to use
+it.
 
 @item libavformat is the library containing the file format handling (mux and
 demux code for several formats). Look at @file{ffplay.c} to use it in a
-player. See @file{libavformat/output-example.c} to use it to generate
-audio or video streams.
+player. See @file{doc/examples/muxing.c} to use it to generate audio or video
+streams.
 
 @end itemize