README/guide is incomplete, missing DNS configurations/tips

[adbenitez]

for someone setting up a server for the first time like me, just following the guide/readme was not enough, ex. the guide assumes you already have a VPS with DNS configured to point to your domain, it would be good to mention that the A record is needed to be added with the domain and corresponding VPS IP, without this it is not possible to start the guide, I had to add this initial records before being able to properly run the cmddeploy run command:

more important to point out: after finishing the deployment, my server was still not able to communicate with Gmail because Reverse DNS lookup records were not configured, the guide doesn't mention this, which is important for federation with the "big providers", the google error:

The IP address sending this message does not have a PTR record setup, or the corresponding forward DNS entry 
does not match the sending IP. As a policy, Gmail does not accept messages from IPs with missing PTR records.
For more information, go to https://support.google.com/a?p=sender-guidelines-ip

after setting up the PTR records in my VPS provider and waiting for some minutes for it to propagate to google DNS servers, then sending messages worked, the PTR can be checked with nslookup or https://www.whatsmydns.net/dns-lookup/ptr-records