[patch] Add IPv6 description for `-T' option in netcat manual

[Nan Xiao]

Hi tech@,

According to netcat source code, the `-T' option not only takes effect
in IPv4 but also IPv6:

        if (Tflag != -1) {
                if (af == AF_INET && setsockopt(s, IPPROTO_IP,
                    IP_TOS, &Tflag, sizeof(Tflag)) == -1)
                        err(1, "set IP ToS");

                else if (af == AF_INET6 && setsockopt(s, IPPROTO_IPV6,
                    IPV6_TCLASS, &Tflag, sizeof(Tflag)) == -1)
                        err(1, "set IPv6 traffic class");
        }

So I think the following patch should be more accurate:

diff --git nc.1 nc.1
index cb391288f15..5588daf87ae 100644
--- nc.1
+++ nc.1
@@ -241,7 +241,7 @@ Cannot be used together with
 or
 .Fl x .
 .It Fl T Ar keyword
-Change the IPv4 TOS value or the TLS options.
+Change the IPv4 TOS/IPv6 Traffic Class value or the TLS options.
 .Pp
 For TLS options,
 .Ar keyword
@@ -269,7 +269,7 @@ for further details).
 Specifying TLS options requires
 .Fl c .
 .Pp
-For the IPv4 TOS value,
+For the IPv4 TOS/IPv6 Traffic Class value,
 .Ar keyword
 may be one of
 .Cm critical ,


Thanks!

-- 
Best Regards
Nan Xiao