Add Page about DOI Generation

[egrace479]

We need a page with information about generating DOIs (for GitHub and Hugging Face) which can be linked to from the Data Policy.

[thompsonmj]

General comment: parentheses are relied on quite a bit, which makes reading a bit bumpy. Sentences could be restructured in some cases to smooth out the ride, e.g. "Dryad is a research data repository similar to Zenodo that allows users to archive their research data and obtain a DOI."