4.1 Commented on Using with async function

Part 4 - Concurrency/1. Scheduling and threading.md

@@ -198,7 +198,7 @@ Finished on threadId:6
 
 We see two things in this example. First, we see that subscribing is no longer blocking. The second thing, which is special about using `async`/`await`, is that the delegate was invoked synchronously but the executing thread changed after the first `await`. That's because `async` functions aren't a single function like you might think. Instead, they are converted into a chain of tasks in [continuation-passing style](http://en.wikipedia.org/wiki/Continuation-passing_style) and the environment assumes the responsibility of scheduling them.
 
-There is also a version of `Defer` that takes an asynchronous function.
+There are also versions `Defer` and `Using` that take an asynchronous function.
 
 
 ## Schedulers