message: Added comment explaining timer::sleep(0)
diff: @@ -617,6 +617,11 @@ impl EventHandler for MainState {
  // Then we flip the screen...
  graphics::present(ctx);
  + // And sleep for 0 seconds.
  + // This tells the OS that we're done using the CPU but it should
  + // get back to this program as soon as it can.
  + // This prevents the game from using 100% CPU all the time
  + // even if vsync is off.
  timer::sleep(Duration::from_secs(0));
  Ok(())
  }
  