[fmt] add source

applications/email.nix

@@ -122,6 +122,8 @@
         serverName  = "${cfg.sub}.${cfg.domain}";
       };
     };
+
+    #https://nixos-mailserver.readthedocs.io/en/latest/add-roundcube.html
     services.roundcube = {
      enable = true;
      # this is the url of the vhost, not necessarily the same as the fqdn of