update readme

src/llmtuner/hparams/parser.py

@@ -320,6 +320,9 @@ def get_infer_args(args: Optional[Dict[str, Any]] = None) -> _INFER_CLS:
         if model_args.adapter_name_or_path is not None and len(model_args.adapter_name_or_path) != 1:
             raise ValueError("vLLM only accepts a single adapter. Merge them first.")
 
+        if model_args.visual_inputs:
+            raise ValueError("vLLM engine does not support MLLM yet. Stay tuned.")
+
     _verify_model_args(model_args, finetuning_args)
     _check_extra_dependencies(model_args, finetuning_args)