tools/dnc: add verbose option to enable the log

Change-Id: If2efb47ecc2c8701ecc41e3318f716e5f584508f
diff --git a/tools/dnc/dnc.1 b/tools/dnc/dnc.1
index 26f847c..a24cf67 100644
--- a/tools/dnc/dnc.1
+++ b/tools/dnc/dnc.1
@@ -60,6 +60,9 @@
 .TP
 .B \-a, \-\-anonymous_cnx
 Activate anonymous connection mode.
+.TP
+.B \-vv, \-\-verbose
+Enable verbose mode.
 
 .SH "ESTABLISHING SSH CONNECTIONS"
 To facilitate SSH connections, \fBdnc\fR establishes a DHT network connection followed by socket creation on port 22. This requires an operational OpenSSH server.