feat: Secondaries reverse proxy: create DNS record for proxy.atsign.org and install cert to match

[gkc]

Is your feature request related to a problem? Please describe. Have a Secondaries reverse proxy available at proxy.atsign.org:443

Describe the solution you'd like Reverse proxy for secondaries was implemented a while ago. Last piece of spiking that implementation is to create a DNS entry for proxy.atsign.org and install cert to match

Additional context Not urgent until customer needs it