Improved Async Task documentation

[kirkmadera]

Feature Request

Improved documentation for Async Tasks

Q	A
New Feature	no
RFC	no
BC Break	no

Summary

Can you please complete the example use case with UserCreationListener under the TaskInvokerListener section? I am having to piece together what App\Listener\UserCreationListener and App\Event\UserCreationEvent are and how to get a valid $dispatcher object in the usage example.

Since this is a paradigm shift in how code is being run, it is confusing to piece things together.

More complete examples in general would be very helpful.