code: public static ResourceRecordSet<NSData> ns(String name, String nsdname) {
      return new NSBuilder().name(name).add(nsdname).build();
    }
docs: creates ns set of ns single {@link denominator.model.rdata.NSData NS} record for the specified
  name.
  
  @param name    ex. {@code denominator.io.}
  @param nsdname ex. {@code ns1.denominator.io.}