Remove outdated sample from readme

Author: kayleg

README.md

@@ -67,53 +67,3 @@ let sub = my_client.subscribe("subscription-name")
 
 When subscribing to a topic, a random subscription name will be generated. To prevent dangling
 subscriptions, you need to explicitly call `subscription.destroy()`.
-
-```
-let topic = Arc::new(pubsub.topic("update-topic".to_owned()));
-tokio::run(lazy(move || {
-    topic
-        .subscribe()
-        .map(|subscription| {
-            println!("Subscribed to topic with: {}", subscription.name);
-            let sub = Arc::new(subscription);
-            let get = sub
-                .clone()
-                .get_messages::<UpdatePacket>()
-                .map(move |(packets, acks)| {
-                    for packet in packets {
-                        println!("Received: {:?}", packet);
-                    }
-
-                    if !acks.is_empty() {
-                        tokio::spawn(sub.acknowledge_messages(acks));
-                    } else {
-                        println!("Cleaning up");
-                        if let Ok(s) = Arc::try_unwrap(sub) {
-                            let destroy = s
-                                .destroy()
-                                .map(|_r| println!("Successfully deleted subscription"))
-                                .map_err(|e| eprintln!("Failed deleting subscription: {}", e))
-                                .then(move |_| {
-                                    drop(pubsub);
-                                    Ok(())
-                                });
-                            tokio::spawn(destroy);
-                        } else {
-                            eprintln!("Subscription is still owned");
-                        }
-                    }
-                })
-                .map_err(|e| println!("Error Checking PubSub: {}", e));
-            tokio::spawn(get);
-        })
-        .map_err(|e| eprintln!("Failed to subscribe: {}", e))
-}));
-```
-
-## Known Caveats
-
-A Hyper Client is retained by each PubSub client for reuse. This can cause the tokio runtime to not exit until the Hyper Client keep-alive terminates. To shutdown the runtime immediately on complete, the PubSub client needs to be explicitly dropped.
-
-```
-drop(my_client);
-```