Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle2ONNX into fix_assign_value_op_bug

Author: risemeup1

README.md

@@ -74,7 +74,8 @@ paddle2onnx --model_dir saved_inference_model \
 如你对导出的 ONNX 模型有优化的需求，推荐使用 `onnx-simplifier`，也可使用如下命令对模型进行优化
 
 ```
-python -m paddle2onnx.optimize --input_model model.onnx --output_model new_model.onnx
+pip install onnxslim
+onnxslim model.onnx slim.onnx
 ```
 
 # 5 代码贡献

README_en.md

@@ -71,6 +71,11 @@ If you need to adjust ONNX models, please refer to [ONNX related tools](./tools/
 
 If you have optimization needs for the exported ONNX model, we recommend using `onnx-simplifier`. You can also optimize the model using the following command.
 
+```
+pip install onnxslim
+onnxslim model.onnx slim.onnx
+```
+
 # 5 Code Contribution
 
 A thriving ecosystem requires everyone's collaborative efforts. Developers can refer to the [Paddle2ONNX Contribution Guide](./docs/zh/Paddle2ONNX_Development_Guide.md) to contribute code to Paddle2ONNX.