This IETF Internet Draft is created using the kramdown-rfc tool found at:
https://github.com/cabo/kramdown-rfc2629
Once you have installed the tools, you should just be able to type kdrfc to generate the
appropriate .txt and .xml files.
More info about using Markdown to create Internet Drafts can be found in a presentation I gave to the IETF Boston community group in June 2018.