Add documentation for atest -U (force upsampling rate for G3RUH)

Author: doismellburning

man/atest.1

@@ -61,6 +61,11 @@ Force G3RUH modem regardless of data rate.
 .BI  "-D " "n"
 Divide audio sample rate by n.
 
+.TP
+.BI  "-U " "n"
+Override automatic upsampling rate for G3RUH,
+improving performance when sample rate to baud ratio is low.
+
 .TP
 .BI  "-h " 
 Print frame contents as hexadecimal bytes.

src/atest.c

@@ -987,6 +987,8 @@ static void usage (void) {
 	dw_printf ("        -J     2400 bps QPSK compatible with MFJ-2400.\n");
 	dw_printf ("\n");
 	dw_printf ("        -D n   Divide audio sample rate by n.\n");
+	dw_printf ("        -U n   Override automatic upsampling rate for G3RUH,\n");
+	dw_printf ("               improving performance when sample rate to baud ratio is low.\n");
 	dw_printf ("\n");
 	dw_printf ("        -h     Print frame contents as hexadecimal bytes.\n");
 	dw_printf ("\n");