fix: error code in connection_error, return token_usage in last frame…

… during using stream/astream

README.md

@@ -68,9 +68,13 @@ pip install --upgrade spark_ai_python
 国内使用:
 ```bash
 pip install -i https://pypi.tuna.tsinghua.edu.cn/simple spark_ai_python
+```
+
+### Upgrade
 
 如果清华源版本不可用,请使用一下命令升级到最新版本:
 
+```sh
 pip install -i  https://repo.model.xfyun.cn/api/packages/administrator/pypi/simple  spark_ai_python --upgrade
 
 ```