Maybe need to enrich `-T' option in netcat manual

[Nan Xiao]

Hi tech@,

For `-T' option explanation in netcat manual:

-T keyword
Change the IPv4 TOS value or the TLS options.

But in fact, the netcat code not only processes 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 maybe the netcat manual should be enriched at least for `-T'
option, thanks!

-- 
Best Regards
Nan Xiao