code: func ServiceWithConfig(configRef *swarmtypes.ConfigReference) ServiceSpecOpt {
  	return func(spec *swarmtypes.ServiceSpec) {
  		ensureContainerSpec(spec)
  		spec.TaskTemplate.ContainerSpec.Configs = append(spec.TaskTemplate.ContainerSpec.Configs, configRef)
  	}
  }
docs: // ServiceWithConfig adds the config reference to the service