fix chapter8 import loadenv

docs/chapter8/Chapter8-Memory-and-Retrieval.md

@@ -154,6 +154,7 @@ hello-agents/
 To allow readers to quickly experience the complete functionality of this chapter, we provide a directly installable Python package. You can install the version corresponding to this chapter with the following commands:
 
 ```bash
+# If you encounter model unavailability in version 0.2.0, please refer to issue#320 or switch to version 0.2.9 for testing.
 pip install "hello-agents[all]==0.2.0"
 python -m spacy download zh_core_web_sm
 python -m spacy download en_core_web_sm

docs/chapter8/第八章 记忆与检索.md

@@ -153,6 +153,7 @@ hello-agents/
 为了让读者能够快速体验本章的完整功能，我们提供了可直接安装的Python包。你可以通过以下命令安装本章对应的版本：
 
 ```bash
+# 0.2.0版本若遇到模型不可用，查看issue#320或切换0.2.9版本进行测试
 pip install "hello-agents[all]==0.2.0"
 python -m spacy download zh_core_web_sm
 python -m spacy download en_core_web_sm