* docs: Add info on using cloud auto-join with Network Segments
Resolves hashicorp/go-discover#57
* Add note about joining network segments
Specifically call out that agents can be configured to join a network
segment by either specifying the Serf LAN port in the join address,
changing the agent's default Serf LAN port by configuring
`ports.serf_lan`, or specifying the port in the `-serf-lan-port`
command line flag.
Resolves#9972
ba7f0b5a0d