Guide for network admins to open ports needed for Hubs

From discussion: https://github.com/mozilla/hubs/discussions/3043

How to whitelist just the servers needed for the necessary port range so network security isn't compromised.

Start with the linked discussion at https://github.com/mozilla/hubs/discussions/3043 and identify the servers and port range Hubs requires. The guide is done when network administrators can whitelist only the necessary servers and ports without unnecessarily weakening network security.

Written by the indexing model from the issue text.