[VM launcher] Document how to set up the cluster when there is UFW firewall

[scottsun94]

Description

https://ray-distributed.slack.com/archives/CN2RGCHRR/p1683615742329169?thread_ts=1683524599.480019&channel=CN2RGCHRR&message_ts=1683615742.329169

The user ran into the issue because of the firewall issue. I followed up in the direct message and he mentioned that when he disabled the UFW firewall, the cluster worked. We need to document what users should try to make it work if there is UFW firewall.

Link

No response

[cszhu]

This P2 issue has seen no activity in the past 2 years. It will be closed in 2 weeks as part of ongoing cleanup efforts.

Please comment and remove the pending-cleanup label if you believe this issue should remain open.

Thanks for contributing to Ray!