User Guide: Writing Actor extension methods

[AutomationPanda]

Write a user guide for the doc site to show how to write Actor extension methods.

• Title: "Writing Actor extension methods"
• User Guide Section: "Interactions"
• Resource Path: /user-guides//user-guides/writing-actor-extension-methods//

Actor extension methods enable developers to create more readable, fluent-like calls. For example, WaitsUntil is an IActor extension method.

[soofm]

Resource path should be: /user-guides/writing-actor-extension-methods/

I can take this one!