Always return "included" where "include" has been requested (#1236)
Always return "included" where "include" has been requested (#1236)

* Always return "included" where "include" has been requested

* Less repetition; clarify empty response

* Fixed em-dash; wrapping

* Feedback change

json-api/json-api,json-api/json-api,json-api/json-api,json-api/json-api,json-api/json-api