[Docs] Update README. (#9970)

(cherry picked from commit 4c50bf00c0)

README.md

@@ -54,14 +54,11 @@ Overload processing: By using the task queue mechanism, the number of schedulabl
 
 ## User Interface Screenshots
 
-![home page](https://user-images.githubusercontent.com/15833811/75218288-bf286400-57d4-11ea-8263-d639c6511d5f.jpg)
-![dag](https://user-images.githubusercontent.com/15833811/75236750-3374fe80-57f9-11ea-857d-62a66a5a559d.png)
-![process definition list page](https://user-images.githubusercontent.com/15833811/75216886-6f479e00-57d0-11ea-92dd-66e7640a186f.png)
-![view task log online](https://user-images.githubusercontent.com/15833811/75216924-9900c500-57d0-11ea-91dc-3522a76bdbbe.png)
-![resource management](https://user-images.githubusercontent.com/15833811/75216984-be8dce80-57d0-11ea-840d-58546edc8788.png)
-![monitor](https://user-images.githubusercontent.com/59273635/75625839-c698a480-5bfc-11ea-8bbe-895b561b337f.png)
-![security](https://user-images.githubusercontent.com/15833811/75236441-bfd2f180-57f8-11ea-88bd-f24311e01b7e.png)
-![treeview](https://user-images.githubusercontent.com/15833811/75217191-3fe56100-57d1-11ea-8856-f19180d9a879.png)
+![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)
 
 ## QuickStart in Docker
 

README_zh_CN.md

@@ -36,19 +36,11 @@ Dolphin Scheduler Official Website
 
 ## 系统部分截图
 
-![home page](https://user-images.githubusercontent.com/15833811/75208819-abbad000-57b7-11ea-8d3c-67e7c270671f.jpg)
-
-![dag](https://user-images.githubusercontent.com/15833811/75209584-93e44b80-57b9-11ea-952e-537fb24ec72d.jpg)
-
-![log](https://user-images.githubusercontent.com/15833811/75209645-c55d1700-57b9-11ea-94d4-e3fa91ab5218.jpg)
-
-![gantt](https://user-images.githubusercontent.com/15833811/75209640-c0986300-57b9-11ea-878e-a2098533ad44.jpg)
-
-![resources](https://user-images.githubusercontent.com/15833811/75209403-11f42280-57b9-11ea-9b59-d4be77063553.jpg)
-
-![monitor](https://user-images.githubusercontent.com/15833811/75209631-b5ddce00-57b9-11ea-8d22-cdf15cf0ee25.jpg)
-
-![security](https://user-images.githubusercontent.com/15833811/75209633-baa28200-57b9-11ea-9def-94bef2e212a7.jpg)
+![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)
 
 ## 近期研发计划