Create validation documents from Stories, Requirements, and test outputs

The mrgvalidate package ingests structured data including text describing user stories and technical requirements, and testing outputs, and creates validation documents by joining these together and inserting them into pre-defined markdown templates that can then be automatically rendered into .docx format. Specifications for input data can be found on the input_formats help page. The companion mrgvalprep package contains helpers for formatting input data to the specification in input_formats.