fix(models-download-path): correct the download path for PDF-Extract-Kit

Adjust the print statement in the how_to_download_models_zh_cn.md guide to reflect
the correct model download location. The path has been updated to specify the 'models'
directory where the model is actually downloaded.

docs/how_to_download_models_zh_cn.md

@@ -42,7 +42,7 @@ pip install modelscope
 # 使用modelscope sdk下载模型
 from modelscope import snapshot_download
 model_dir = snapshot_download('wanderkid/PDF-Extract-Kit')
-print(f"模型文件下载路径为：{model_dir}")
+print(f"模型文件下载路径为：{model_dir}/models")
 ```
 
 ## 额外步骤