Fix VTY documentation error introduced  in "bind" VTY port change

In 99ae401e490e60fc07bef7eacc478be7bdcc9f5a we introduced the ability
to specify the TCP port to which the VTY should bind.  However, the VTY
dcumentation wasn't extended accordingly, causing virtually all master
build jobs to fail.

Change-Id: I54fb0ca0d3a884a64a349b22de70f3d9bd1a6d54
diff --git a/src/vty/vty.c b/src/vty/vty.c
index 7f6c225..abce887 100644
--- a/src/vty/vty.c
+++ b/src/vty/vty.c
@@ -1616,7 +1616,8 @@
 /* vty bind */
 DEFUN(vty_bind, vty_bind_cmd, "bind A.B.C.D [<0-65535>]",
       "Accept VTY telnet connections on local interface\n"
-      "Local interface IP address (default: " VTY_BIND_ADDR_DEFAULT ")\n")
+      "Local interface IP address (default: " VTY_BIND_ADDR_DEFAULT ")\n"
+      "Local TCP port number\n")
 {
 	talloc_free((void*)vty_bind_addr);
 	vty_bind_addr = talloc_strdup(tall_vty_ctx, argv[0]);