Update hyperlink in Chinese Overview doc (#5307)

* update hyperlinks for two PR related subjects

* Update hyperlinks for two PR related subjects

* Update links to relative path

Author: caolonghao

docs/dev_guides/Overview_cn.md

@@ -6,8 +6,8 @@
 
 - [新建一个 ISSUE 来反馈 bug](https://github.com/PaddlePaddle/Paddle/issues/new/choose)
 - [新建一个 ISSUE 来提出新功能需求](https://github.com/PaddlePaddle/Paddle/issues/new/choose)
-- [提 PR 来修复一个 bug](https://www.paddlepaddle.org.cn/documentation/docs/zh/guides/10_contribution/local_dev_guide_cn.html)
-- [提 PR 来实现一个新功能](https://www.paddlepaddle.org.cn/documentation/docs/zh/guides/10_contribution/local_dev_guide_cn.html)
+- [提 PR 来修复一个 bug](./code_contributing_path_cn.html)
+- [提 PR 来实现一个新功能](./code_contributing_path_cn.html)
 - [优化我们的文档](https://github.com/PaddlePaddle/docs/wiki/%E6%96%87%E6%A1%A3%E8%B4%A1%E7%8C%AE%E6%8C%87%E5%8D%97)
 
 感谢你对飞桨开源项目的贡献！