update dco link

Signed-off-by: NNEEN <neen.yang@huawei.com>

en/contribute/how-to-contribute.md

@@ -8,7 +8,7 @@
 
 You must sign the Developer Certificate of Origin (DCO) before you can contribute to the community.
 
-Click [here](https://dco.openharmony.io/sign/Z2l0ZWUlMkZvcGVuX2hhcm1vbnk=) to sign the DCO, and click [here](https://dco.openharmony.io/check-sign-status) to check the signing status.
+Click [here](https://dco.openharmony.cn/#/sign) to sign the DCO, and click [here](https://dco.openharmony.cn/#/check-sign-status) to check the signing status.
 
 **Code of Conduct**
 

zh-cn/contribute/参与贡献.md

@@ -8,7 +8,7 @@
 
 您必须首先签署“开发者原创声明”，然后才能参与社区贡献。
 
-点击[这里](https://dco.openharmony.io/sign/Z2l0ZWUlMkZvcGVuX2hhcm1vbnk=)签署，点击[这里](https://dco.openharmony.io/check-sign-status)查询签署状态。
+点击[这里](https://dco.openharmony.cn/#/sign)签署，点击[这里](https://dco.openharmony.cn/#/check-sign-status)查询签署状态。
 
 #### 行为准则