Update direwolf.c

Co-Authored-By: Vladimir <ew1abz@gmail.com>

Author: ThomasHabets

direwolf.c

@@ -1251,7 +1251,7 @@ static void usage (char **argv)
 	dw_printf ("    -c fname       Configuration file name.\n");
 	dw_printf ("    -l logdir      Directory name for log files.  Use . for current.\n");
 	dw_printf ("    -r n           Audio sample rate, per sec.\n");
-	dw_printf ("    -m             Use metric instead of US customary units.\n");
+	dw_printf ("    -m             Use metric instead of imperial units.\n");
 	dw_printf ("    -n n           Number of audio channels, 1 or 2.\n");
 	dw_printf ("    -b n           Bits per audio sample, 8 or 16.\n");
 	dw_printf ("    -B n           Data rate in bits/sec for channel 0.  Standard values are 300, 1200, 2400, 4800, 9600.\n");