Refine some explanations, add code style markup to increase readability
Update data-in-modules to describe simplified structures

This describes the data-in-modules hiera.yaml for format:3 and then te
difference in format:2 - this was much more straight forward than
explaining it in detail for format: 2.

This is half of the edits, as binder_config.yaml also has been
simplified somewhat.
This adds a first draft of how to use data in modules in rspec. (w.i.p)