修改说明文档

README.md

@@ -27,5 +27,8 @@ python train_vgg16.py --data-path dataset/imagenette2-320 --output-dir checkpoin
 
 ## 模型训练权重转换为onnx
 ```shell
-python export_onnx.py 
+python export_onnx.py --model_dir checkpoints/alexnet
+```
+```shell
+python export_onnx.py --model_dir checkpoints/vgg16
 ```