Correctly print 12 bits as --short payload size in usage.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/audiowmark.cc

@@ -57,7 +57,7 @@ print_usage()
   printf ("Global options:\n");
   printf ("  --strength <s>        set watermark strength              [%.6g]\n", Params::water_delta * 1000);
   printf ("  --linear              disable non-linear bit storage\n");
-  printf ("  --short               enable short payload mode (16 bits)\n");
+  printf ("  --short               enable short payload mode (12 bits)\n");
   printf ("  --key <file>          load watermarking key from file\n");
   printf ("  -q, --quiet           disable information messages\n");
   printf ("\n");