Resolve "Test CQL evaluation and QuestionnaireResponse pre-population for the Questionnaires and Libraries in CQF-US." and "Move CQF-US README to Authoring Documentation."

[dmuylwyk]

Closes #29

Closes #30

[dmuylwyk]

Hi, @brynrhodes. Could you please give this a review?

These changes complete #30 in full.

These changes only partially address #29 at this time. Please refer to this comment regarding current state:

• Test CQL evaluation and QuestionnaireResponse pre-population for the Questionnaires and Libraries in CQF-US. #29 (comment)

The two outstanding issues that are blocking me:

1. Error loading/resolving library FHIRHelpers, version 4.1.0, is preventing testing with $populate. Unsure if this is an issue when updating CQF tooling or if this is something I need to modify directly.
2. Executing CQL in the project works for in-context Patient but not Coverage. Looking at older test results, it appears as though this used to work for the existing Questionnaires so I suspect this may also be related to updating CQF tooling.

I'm blocked by these issues, and I would appreciate your insight. Thanks!