Responses should be an array, not a map

[daniel-white]

In order to promote reuse of responses and reducing the duplication of the response key, the response object should be an array of responses that have a name property.

Instead of

responses:
  ok:
    contentType: application/json
  badRequest:
    $ref: '#/components/responses/badRequest'

Consider

responses:
  - name: ok
    contentType: application/json
  - $ref: '#/components/responses/badRequest'

[handrews]

Thanks @daniel-white - this is a duplicate of #25 so I'm going to close it, but please feel free to comment there, or on the more general object vs array discussion in #32.