message: docs(server): tweaks to server doc example
diff: //! ## Example
  //!
  //! ```no_run
  -//! use hyper::{Body, Error, Response, Server};
  +//! use std::convert::Infallible;
  +//! use std::net::SocketAddr;
  +//! use hyper::{Body, Request, Response, Server};
  //! use hyper::service::{make_service_fn, service_fn};
  //!
  +//! async fn handle(_req: Request<Body>) -> Result<Response<Body>, Infallible> {
  +//! Ok(Response::new(Body::from("Hello World")))
  +//! }
  +//!
  //! # #[cfg(feature = "runtime")]
  //! #[tokio::main]
  //! async fn main() {
  //! // Construct our SocketAddr to listen on...
  -//! let addr = ([127, 0, 0, 1], 3000).into();
  +//! let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
  //!
  //! // And a MakeService to handle each connection...
  -//! let make_service = make_service_fn(|_| async {
  -//! Ok::<_, Error>(service_fn(|_req| async {
  -//! Ok::<_, Error>(Response::new(Body::from("Hello World")))
  -//! }))
  +//! let make_service = make_service_fn(|_conn| async {
  +//! Ok::<_, Infallible>(service_fn(handle))
  //! });
  //!
  //! // Then bind and serve...
  -//! let server = Server::bind(&addr)
  -//! .serve(make_service);
  +//! let server = Server::bind(&addr).serve(make_service);
  //!
  -//! // Finally, spawn `server` onto an Executor...
  +//! // And run forever...
  //! if let Err(e) = server.await {
  //! eprintln!("server error: {}", e);
  //! }
  