code: func (u *DockerRegistryURL) AddLibraryNamespace() {
  	// If the image name does not contain '/', it is intended to be an official
  	// image; so we add the `library` namespace to the URL.
  	if !strings.Contains(u.ImageName, "/") {
  		u.ImageName = fmt.Sprintf("library/%s", u.ImageName)
  	}
  }
docs: // AddLibraryNamespace explicitly appends the `library` namespace used for
  // official images.