Create Guide for using DPV as CSV/JSON (non-sem-web use-cases)

[coolharsh55]

The DPV is defined using semantic web standards (RDF). For use-cases that do not use semantic web, DPV is still useful as a controlled vocabulary, such as an use-cases that uses the list of purposes as suggestions in a form. To support such use-cases, this guide will explain how to use DPV - in particular as a CSV serialisation is provided to support such uses.