Style guide

[RobertJCarroll]

We need to develop a style guide to ensure all of our contributions are consistent.

[torstees]

@liberaliscomputing Some info that may be useful when you are working on this:

1. When you create a file in pagecontent, when filenames are all lowercase, the header will be automagically altered to capitalize: So fhir_basics becomes Fhir Basics. To get FHIR to be all caps, that filename has to be FHIR_Basics.md (not sure the B is required)

2. I find our prior approach to instances to be confusing and suggest we work with all pieces of a given "component" together. So, for my ResearchStudy example, I put the Study, Group, Patients and ResearchSubjects in a single file named Example-something-or-another.