Migration to schema-generated specifications

In order to:

1. Maintain updated the specifications
2. Be able to provide them in multiple languages
3. Being able to track what properties are already defined
4. Populate properly the database of properties
5. Have a shared image for all contributions
6. Reduce the burden of work for the contributors (it will be reduced to just the documented json schema and the examples)

It has been decided that the description of the properties of the data models will be included in the schemas defining the data models (or those linked through $ref). so during next days, you will see minor changes in the schema.json of every data model in the initiative.

And although it will be announced previously all the spec.md will be replaced by an automatically generated (based on the info). See an example here. Design could be modified so any suggestion will be assessed and eventually implemented.

Customization will be possible through a new file named notes.yaml

This is taking most of our resources and impact on our bandwidth t provide answers to the PR, but we expect that this will reduce our workload significantly so we will be more agile after this change.