The file structure
Everything within the docs/ folder--and nothing else--gets published to Read The Docs, where the files are searchable and get a nice browsable table of contents sidebar. The only files in the root directory of the repo (above docs/) are configuration files and the main repo README.md, which is what you find at https://github.com/CivicActions/handbook.
Within the docs folder, the folder and file structure loosely maps to our practice areas and working groups.
Each folder should contain a README.md file with some introduction text for that section. We don't need tables of contents, because that is provided by Read The Docs.