nixos/r53-ddns: Add new option for record ttl

nixos/modules/services/networking/r53-ddns.nix

···
         '';
       };
 
+      ttl = mkOption {
+        type = types.int;
+        description = "The TTL for the generated record";
+      };
+
       environmentFile = mkOption {
         type = types.str;
         description = ''
···
       serviceConfig = {
         ExecStart =
           "${pkg}/bin/r53-ddns -zone-id ${cfg.zoneID} -domain ${cfg.domain}"
-          + lib.optionalString (cfg.hostname != null) " -hostname ${cfg.hostname}";
+          + lib.optionalString (cfg.hostname != null) " -hostname ${cfg.hostname}"
+          + lib.optionalString (cfg.ttl != null) " -ttl ${toString cfg.ttl}";
         EnvironmentFile = "${cfg.environmentFile}";
         DynamicUser = true;
       };