nginx service improvements

Adding Restart, RestartSec, StartLimitInterval to ensure that the service
is started in case if it can't assign (bind) the address as often it takes longer
for the network (e.g. dhcpcd) to get the IP assigned.

nixos/modules/services/web-servers/nginx/default.nix

@@ -102,6 +102,9 @@ in
         '';
       serviceConfig = {
         ExecStart = "${nginx}/bin/nginx -c ${configFile} -p ${cfg.stateDir}";
+        Restart = "on-failure";
+        RestartSec = "10s";
+        StartLimitInterval = "1min";
       };
     };