As more and more contributors are helping build SAFETAG, we realized that the existing guidance on the structure had fallen out of line with the current setup, and how the SAFETAG content is getting mapped into the Content as Code framework.
We have now updated and combined our disparate documentation on the structure of SAFETAG in light of recent feedback and (in the ongoing effort to polish the repository) have uploaded it as a CONTRIBUTING.md file
Finally, there's an updated release (ironically not including the above documents yet) which rolls up the changes from the recent write-sprint.