Fix API docs for GET /secrets/{id}, GET /secrets

The swagger.yml defined these endpoints to return
a "ServiceSpec" instead of a "SecretSpec".

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

api/swagger.yaml

@@ -2779,7 +2779,7 @@ definitions:
         type: "string"
         format: "dateTime"
       Spec:
-        $ref: "#/definitions/ServiceSpec"
+        $ref: "#/definitions/SecretSpec"
 paths:
   /containers/json:
     get: