Link aec.c in README.md

README.md

@@ -153,7 +153,7 @@ output and specifying `AEC_NO_FLUSH`. The function will return if either
 the input runs empty or the output buffer is full. The calling
 function can check `avail_in` and `avail_out` to see what occurred. The
 last call to `aec_encode()` must set `AEC_FLUSH` to drain all
-output. aec.c is an example of streaming usage of encoding and
+output. [aec.c](src/aec.c) is an example of streaming usage of encoding and
 decoding.
 
 ### Output: