code: func (api *API) ZoneSetVanityNS(zoneID string, ns []string) (Zone, error) {
  	zoneopts := ZoneOptions{VanityNS: ns}
  	zone, err := api.EditZone(zoneID, zoneopts)
  	if err != nil {
  		return Zone{}, err
  	}
  
  	return zone, nil
  }
docs: // ZoneSetVanityNS sets custom nameservers for the zone.
  // These names must be within the same zone.