message: docs(examples): gateway: remove extra slash for uri
  The PathAndQuery already contains the leading slash, which erroneously
  sets the proxied path to "//.." and not "/..".
diff: @@ -26,9 +26,12 @@ async fn main() {
  // returns a Response into a `Service`.
  Ok::<_, Error>(service_fn(move |mut req| {
  let uri_string = format!(
  - "http://{}/{}",
  + "http://{}{}",
  out_addr_clone,
  - req.uri().path_and_query().map(|x| x.as_str()).unwrap_or("")
  + req.uri()
  + .path_and_query()
  + .map(|x| x.as_str())
  + .unwrap_or("/")
  );
  let uri = uri_string.parse().unwrap();
  *req.uri_mut() = uri;
  