Align Reference template with new quality expectations

[aidanatwork]

Align Reference template with new quality expectations

Description

Doc Type Name: Reference

Directory: https://github.com/thegooddocsproject/templates/tree/master/reference

Sub-tasks

1. Create reference-template.md and write content for it
2. Create reference-guide.md and write content for it
3. Create reference-theory.md and write content for it. This is any research and conclusions about best practices that support what you are presenting to the end user in the other files. This can be an empty stub file.

We already have an attempt at template files in this directory, but they need to be renamed to match our naming convention. Extraneous files also need to be deleted. Should be general enough to encompass both API reference pages and other types of reference pages.

Helpful Resources

https://documentation.divio.com/reference/