Update native_api doc to match the change in the `get_model_info` endpoint (#7660)

Co-authored-by: Lifu Huang <lifu.hlf@gmail.com>
Co-authored-by: Xinyuan Tong <115166877+JustinTong0323@users.noreply.github.com>

docs/backend/native_api.ipynb

@@ -96,7 +96,8 @@
     "\n",
     "- `model_path`: The path/name of the model.\n",
     "- `is_generation`: Whether the model is used as generation model or embedding model.\n",
-    "- `tokenizer_path`: The path/name of the tokenizer."
+    "- `tokenizer_path`: The path/name of the tokenizer.\n",
+    "- `preferred_sampling_params`: The default sampling params specified via `--preferred-sampling-params`. `None` is returned in this example as we did not explicitly configure it in server args."
    ]
   },
   {
@@ -113,6 +114,7 @@
     "assert response_json[\"model_path\"] == \"qwen/qwen2.5-0.5b-instruct\"\n",
     "assert response_json[\"is_generation\"] is True\n",
     "assert response_json[\"tokenizer_path\"] == \"qwen/qwen2.5-0.5b-instruct\"\n",
+    "assert response_json[\"preferred_sampling_params\"] is None\n",
     "assert response_json.keys() == {\n",
     "    \"model_path\",\n",
     "    \"is_generation\",\n",