Generate documentation of the YAML document schema

[honzajavorek]

• Use JSON Schema and pydantic https://docs.pydantic.dev/latest/concepts/fields/#customizing-json-schema
• Provide descriptions and examples
• Use the output to generate docs that people can read and contribute their document according to
• Could be as a template YAML file which is offered to a person pre-filled, with all sorts of comments and examples