indeo3: add @file doxy and a link to multimedia wiki documentation

libavcodec/indeo3.c

 /*
- * Intel Indeo 3 (IV31, IV32, etc.) video decoder for ffmpeg
- * written, produced, and directed by Alan Smithee
- *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
@@ -19,6 +16,15 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+/**
+ * @file
+ * Intel Indeo 3 (IV31, IV32, etc.) video decoder for FFmpeg
+ * written, produced, and directed by Alan Smithee
+ *
+ * For some documentation see:
+ * http://wiki.multimedia.cx/index.php?title=Indeo_3
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>