Currently, the README.md at data models level (inside every directory in a Subject) explaining the contents of the data models is automated, and therefore there is no need to be contributed by the contributors. See an example here for the weather forecast.
Thus, the README.md is based on the examples provided, the specification and the model.yaml.
Soon the README.md for the Subject will be also automated.
Slack channel
Validate a payload with a data model