Geoproperties were formerly not documented because it was not possible to include the description into the definition of the data model.
Previously, the definition of Geojson property was retrieved from the original source, which prevents the documentation to be added. No its has been cloned into the common-schema.json, and the description has been added. As a consequence, they appear in the specification of all data models (all of them have been updated) tonight.
Additionally, the schema checker (The test which assesses if a JSON schema is properly documented) no longer accepts any undocumented property (Example). So if you want a data model to be accepted then you need to get a 0.
The contribution manual has been adapted accordingly.