Documentation page for apps that require domain & link in all app inithooks that require domain

[JedMeister]

We should have a doc page that explains the context of apps that require a domain and give info about domain usage. There should be a link to this doc page shown on the "set domain" inithook on all apps that require a domain be set.

The TL;DR of the doc page should cover:

• note that some apps require domain and simple explanation of why
• server MUST have either a static IP or domain updated via dynamic DNS
• chosen domain name MUST point to server
• ideal: A or CNAME DNS record pointing to server static IP
  • a local DNS server (e.g. router, dnsmasq, pihole, etc) is an option (will only resolve for users using local DNS)
• workaround: HubDNS - static IP not required although suggested for production (testing or production)
• workaround: edit local hosts (testing only)
• workaround: use IP as "domain" static IP required (testing only)

Pinned to 19.0 - but sooner is better