When spec references externalized files, they're not copied in

Following best practices, an OAS should externalize schemas and examples. For example:

      requestBody:
        content:
          application/json:
            schema:
              $ref: 'schemas/dog-schema.yaml'
            example:
              $ref: 'examples/dog.json'

Although the project can be created, the validator will fail because these external folders are not copied in. We will need to first establish a standard so that we can accept these externalized files.