Relax related_identifier_schema.relationType "format": "uri" and add option of annotation_schema.
Created by: agbeltran
Ideally, the relationType in the related_identifier_schema should be an ontology term from a controlled vocabulary. However, we've got examples with simply strings.
The type should probably have been an annotation_schema. So, I will extend the types with the option of relaxing "format":"uri" and add also annotation_schema as possible value.