Merge pull request #1017 from LYUyang-JK/patch-43

Update rank.md

Author: wenlixiu

program-docs/docs/introduction/rank.md

@@ -14,7 +14,7 @@ sidebar: rank
 ![Alt text](../../img/flow/rank/1555413108354.png)
 
 **搜索流量接入流程图**
- ![Alt text](../../img/flow/rank/1555413083846.png)
+ ![Alt text](https://b.bdstatic.com/searchbox/icms/searchbox/img/替换图片.png)