Doc: Add more details about testing framework

[robbavey]

Currently the testing the ruby script portion of the documentation describes how to use the testing framework with a single, relatively straightforward, example, and is lacking further examples on the features and syntax.

This blog post provides further more complex examples, which may be helpful to also include in the documentation, along with a description of how to use parameters, in_event and expect possibly along the lines of the documentation for the expected methods in the ruby script file