code: func setup(c *caddy.Controller) error {
  	upstreams, err := NewStaticUpstreams(c.Dispenser)
  	if err != nil {
  		return err
  	}
  	httpserver.GetConfig(c).AddMiddleware(func(next httpserver.Handler) httpserver.Handler {
  		return Proxy{Next: next, Upstreams: upstreams}
  	})
  	return nil
  }
docs: // setup configures a new Proxy middleware instance.