Update ipv6-relay-howto page
https://lists.torproject.org/pipermail/tor-relays/2014-May/004610.html suggests updating https://people.torproject.org/~linus/ipv6-relay-howto.html now that some of the ipv6 bugs are fixed.
I could imagine this should be either a wiki page or a first-class website page. Wiki seems slightly smarter since the general area is still in flux.