Add caddy configuration in documentation

[SebastianMoyano]

Hi, before anything, just wanted to thank the people involved in this project, it has a beautiful UI I was using amber, but I changed when I saw the clean UI that overseer has, so thank you very much for this project!

So continuing with the subject. I just started using caddy, it is very simple and straight forward way to make a reverse proxy, I'm not very savvy in this area so the easier the better for me. I read that overseer doesn't have a direct way to use reverse proxy, so I used a second domain(no Ip) pointing to the same server, only port forwarding port 443 and used this in the caddy file and it worked.

mysite.com {
        reverse_proxy localhost:5055
}

So maybe adding something in regard to this (caddy) in documentation would be very helpful for people like me that haven't used Nginx yet.

This is my first time using the discussion area int github and english its not my native language so im sorry before hand.