📝 Update reference docs for ORJSONResponse and UJSONResponse

docs/en/docs/reference/responses.md

@@ -22,7 +22,13 @@ from fastapi.responses import (
 
 ## FastAPI Responses
 
-There are a couple of custom FastAPI response classes, you can use them to optimize JSON performance.
+There were a couple of custom FastAPI response classes that were intended to optimize JSON performance.
+
+However, they are now deprecated as you will now get better performance by using a [Response Model - Return Type](https://fastapi.tiangolo.com/tutorial/response-model/).
+
+That way, Pydantic will serialize the data into JSON bytes on the Rust side, which will achieve better performance than these custom JSON responses.
+
+Read more about it in [Custom Response - HTML, Stream, File, others - `orjson` or Response Model](https://fastapi.tiangolo.com/advanced/custom-response/#orjson-or-response-model).
 
 ::: fastapi.responses.UJSONResponse
     options: