Sorry but your sample Code is really bad and in no way asynchronous. Everything is executed synchronously!
Just use your Code in a Winforms-Project and include a Thread.Sleep into ComputeValue. You will see that your code doesn't do what you've intented. There is a missing call to Task.Run or Task.Factory.StartNew to ultimately span an async operation.
You took a 2+2 example of the Await and Azync Functions and left it like that. It was not converted into an Einstien Outer-space formula. I Like It.
You did a very good job on this short, but very informative, article. Now I do not need to buy a 600 page book on something you explained in a few hundred words.
Keep up the good work.