docs(examples): add an example using an HTTP/2 client

examples/client_http2.rs

@@ -0,0 +1,34 @@
+#![deny(warnings)]
+extern crate hyper;
+
+extern crate env_logger;
+
+use std::env;
+use std::io;
+
+use hyper::Client;
+use hyper::header::Connection;
+use hyper::http2;
+
+fn main() {
+    env_logger::init().unwrap();
+
+    let url = match env::args().nth(1) {
+        Some(url) => url,
+        None => {
+            println!("Usage: client <url>");
+            return;
+        }
+    };
+
+    let mut client = Client::with_protocol(http2::new_protocol());
+
+    // `Connection: Close` is not a valid header for HTTP/2, but the client handles it gracefully.
+    let mut res = client.get(&*url)
+        .header(Connection::close())
+        .send().unwrap();
+
+    println!("Response: {}", res.status);
+    println!("Headers:\n{}", res.headers);
+    io::copy(&mut res, &mut io::stdout()).unwrap();
+}