Add documentation for atest -e (set a Bit Error Rate)

Author: doismellburning

man/atest.1

@@ -72,6 +72,10 @@ Amount of effort to try fixing frames with an invalid CRC.
 1 = Try to fix only a single bit.
 more = Try modifying more bits to get a good CRC.
 
+.TP
+.BI  "-e " "n"
+Artificially introduce a desired Bit Error Rate (BER) for testing.
+
 .TP
 .BI  "-L " 
 Error if Less than this number decoded.

src/atest.c

@@ -994,6 +994,7 @@ static void usage (void) {
 	dw_printf ("               0 (default) = consider only correct frames.  \n");
 	dw_printf ("               1 = Try to fix only a single bit.  \n");
 	dw_printf ("               more = Try modifying more bits to get a good CRC.\n");
+	dw_printf ("        -e n   Artificially introduce a desired Bit Error Rate (BER) for testing.\n");
 	dw_printf ("\n");
 	dw_printf ("        -d x   Debug information for FX.25.  Repeat for more detail.\n");
 	dw_printf ("\n");