Tell HN: HN's IPv6 address is down

HN on IPv4 works fine (209.216.230.207) but appears down on IPv6 (2606:7100:1:67::26), checked from multiple points. None of the HN status monitors appear to catch this. “Happy eyeballs” keeps everything working fine on a dual IPv4/IPv6 network, but in my case I am visiting via a proxy that apparently prefers IPv6, switching over only when it hits a timeout. (It’s a testament to the gradual IPv6 rollout that this works 99.9% of the time!).