This is an optional change, to help diagnose relay address resolution issues. Relays (and bridges) should log the address chosen using each address resolution method, when: * address resolution succeeds, * address resolution fails, * reachability checks fail, or * publishing the descriptor fails. These logs should be rate-limited separately for successes and failures. The logs should tell operators to set the Address torrc option for IPv4 and IPv6 (if available). See proposal 312, section 3.5.5: https://gitweb.torproject.org/torspec.git/tree/proposals/312-relay-auto-ipv6-addr.txt#n1083