avcodec/h263dec: Document padding_bug_score heuristic used for wrong stuffing

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/h263dec.c

@@ -318,6 +318,7 @@ static int decode_slice(MpegEncContext *s)
 
     av_assert1(s->mb_x == 0 && s->mb_y == s->mb_height);
 
+    // Detect incorrect padding with wrong stuffing codes used by NEC N-02B
     if (s->codec_id == AV_CODEC_ID_MPEG4         &&
         (s->workaround_bugs & FF_BUG_AUTODETECT) &&
         get_bits_left(&s->gb) >= 48              &&