[doc] Fix docs deadlink in readme (#9972)

* [Docs] Fix docs url.

* Update README.md

* Update README.md

* Update README_zh_CN.md

Co-authored-by: Jiajie Zhong <zhongjiajie955@gmail.com>
(cherry picked from commit e51d0fb594)

README.md

@@ -54,11 +54,11 @@ Overload processing: By using the task queue mechanism, the number of schedulabl
 
 ## User Interface Screenshots
 
-![dag](https://github.com/apache/dolphinscheduler/tree/dev/images/en_US/dag.png)
-![data-source](https://github.com/apache/dolphinscheduler/tree/dev/images/en_US/data-source.png)
-![home](https://github.com/apache/dolphinscheduler/tree/dev/images/en_US/home.png)
-![master](https://github.com/apache/dolphinscheduler/tree/dev/images/en_US/master.png)
-![workflow-tree](https://github.com/apache/dolphinscheduler/tree/dev/images/en_US/workflow-tree.png)
+![dag](./images/en_US/dag.png)
+![data-source](./images/en_US/data-source.png)
+![home](./images/en_US/home.png)
+![master](./images/en_US/master.png)
+![workflow-tree](./images/en_US/workflow-tree.png)
 
 ## QuickStart in Docker
 

README_zh_CN.md

@@ -36,11 +36,11 @@ Dolphin Scheduler Official Website
 
 ## 系统部分截图
 
-![dag](https://github.com/apache/dolphinscheduler/tree/dev/images/zh_CN/dag.png)
-![data-source](https://github.com/apache/dolphinscheduler/tree/dev/images/zh_CN/data-source.png)
-![home](https://github.com/apache/dolphinscheduler/tree/dev/images/zh_CN/home.png)
-![master](https://github.com/apache/dolphinscheduler/tree/dev/images/zh_CN/master.png)
-![workflow-tree](https://github.com/apache/dolphinscheduler/tree/dev/images/zh_CN/workflow-tree.png)
+![dag](./images/zh_CN/dag.png)
+![data-source](./images/zh_CN/data-source.png)
+![home](./images/zh_CN/home.png)
+![master](./images/zh_CN/master.png)
+![workflow-tree](./images/zh_CN/workflow-tree.png)
 
 ## 近期研发计划