Add endpoint links.

app/Api/V1/Controllers/Summary/BasicController.php

@@ -87,6 +87,9 @@ class BasicController extends Controller
     }
 
     /**
+     * This endpoint is documented at:
+     * https://api-docs.firefly-iii.org/#/summary/getBasicSummary
+     *
      * @param DateRequest $request
      *
      * @return JsonResponse