JSON Schema link broken

[jvansanten]

I clicked on "JSON Schema" link in the README, thinking it would take me to the actual schema, but got a 404 instead. It looks like that was intended to point to the JSON Schema docs themselves, but their site was reorganized at some point. Maybe that link should point to https://json-schema.org/overview/what-is-jsonschema?

rest-api-doc/README.md

Line 144 in 60099b8

The `metadata` object contains the metadata of the record proper. All records have a `$schema` key, which links to a [JSON schema](https://json-schema.org/understanding-json-schema/index.html) (draft 4) that the record metadata obeys. Detailed documentation about the possible fields for each schema and their meaning can be found in the [schema documentation](https://inspire-schemas.readthedocs.io/en/latest/schemas/).