DOC: restructure Stoplight docs to be more modular

[jeff-knurek]

Problem

The documentation in Stoplight 1) includes content that is not relevant to the project 2) is unclear in what it really represents unless to new people 3) is saved in one really giant json file 4) because it's in one file, it's not "close to the code" that it represents

Proposed solution

• make use of the Table of Contents file (toc) in Stoplight: https://meta.stoplight.io/docs/platform/4.-documentation/d.table-of-contents.md
• split the giant json file into smaller parts, and move those smaller parts to where the code they represent are

Resources

• https://theiofoundation.stoplight.io/docs/projectlockdown/docs/index.md

[jeff-knurek]

merging that last commit closed this issue, but that was only part of the work needed on this task, so I'm re-opening

next step is that now that a TOC file is in place, to split the giant json into smaller chunks. an idea that might work is to first only split the db models & the api endpoints. that might make it just another smaller PR which can also allow for making sure the TOC is also working with the changes being made