Updated AsyncRelayCommand docs

Author: Sergio0694

docs/mvvm/AsyncRelayCommand.md

@@ -15,7 +15,8 @@ The [`AsyncRelayCommand`](https://docs.microsoft.com/dotnet/api/microsoft.toolki
 
 `AsyncRelayCommand` and `AsyncRelayCommand<T>` have the following main features:
 
-- They extend the functionalities of the non-asynchronous commands included in the library, with support for `Task`-returning delegates.
+- They extend the functionalities of the synchronous commands included in the library, with support for `Task`-returning delegates.
+- They can wrap asynchronous functions with an additional `CancellationToken` parameter to support cancelation, and they expose a `CanBeCanceled` and `IsCancellationRequested` properties, as well as a `Cancel` method.
 - They expose an `ExecutionTask` property that can be used to monitor the progress of a pending operation, and an `IsRunning` that can be used to check when an operation completes. This is particularly useful to bind a command to UI elements such as loading indicators.
 - They implement the `IAsyncRelayCommand` and `IAsyncRelayCommand<T>` interfaces, which means that viewmodel can easily expose commands using these to reduce the tight coupling between types. For instance, this makes it easier to replace a command with a custom implementation exposing the same public API surface, if needed.