update legacy TorRelayGuide and Exit Notice HTML page w/r/t DNSEL changes
While the wiki TorRelayGuide claims to be no longer maintained, the new documentation is difficult to navigate and appears devoid of technical information--certainly any present is well hidden.
Please spend a few minutes updating the legacy documentation page to reflect DNSEL changes as described in
https://lists.torproject.org/pipermail/tor-project/2020-March/002759.html
Please also revise the template exit notice.