code: func DockerDaemon(c *dockerutil.Client) *DockerDaemonRegistry {
  	e := multiExtractor(
  		newFileExtractor(c),
  		newCMDExtractor(c),
  	)
  	return &DockerDaemonRegistry{
  		docker:    c,
  		extractor: e,
  	}
  }
docs: // DockerDaemon returns an empire.ImageRegistry that uses a local Docker Daemon
  // to extract procfiles and resolve images.