* Add eth/67
* Listen to eth/66 on a separate port
* Fix compilation error
* Fix cfg66.ListenAddr
* Update erigon ports in README
* Expose port 30304 in docker
* P2pProtocolVersionFlag instead of second sentry
* Remove "66 by default" from usage
* Small comment
--nat stun is an automatic external IP detection alternative to manual --nat extip option.
It can be used both at home or on production servers without any extra setup.
It is fast (up to 5 ms) and more reliable than alternatives (as the request goes to the public internet).
This auto-detection is useful to run multiple instances of a service in cloud environments
where the node IPs are not known in advance.
