update zh-cn/application-dev/website.md.

在示例教程节点下增加开发案例节点
Signed-off-by: sunxianlei <sunxianlei@foxmail.com>

zh-cn/application-dev/website.md

@@ -659,6 +659,7 @@
     - [cem工具](tools/cem-tool.md)
     - [anm工具](tools/anm-tool.md)
 - 示例教程
+  - [开发案例](https://gitee.com/openharmony/docs/blob/master/zh-cn/third-party-cases/Readme-CN.md)
   - [示例代码](https://gitee.com/openharmony/applications_app_samples/blob/OpenHarmony-3.2-Release/README_zh.md)
   - [Codelabs](https://gitee.com/openharmony/codelabs/blob/master/README.md)
 - API参考