code: func (d *Discover) Help() string {
  	d.once.Do(d.initProviders)
  
  	h := []string{globalHelp}
  	for _, name := range d.Names() {
  		h = append(h, d.Providers[name].Help())
  	}
  	return strings.Join(h, "\n")
  }
docs: // Help describes the format of the configuration string for address discovery
  // and the various provider specific options.