Update README.md

Author: todd5167

README.md

@@ -328,4 +328,6 @@ into
 
 # FlinkX & FlinkStreamSQL钉钉交流群
 
-![image](images/钉钉群.jpg)
+<div align=center>
+    <img src=https://user-images.githubusercontent.com/11881814/76816457-3df44800-683b-11ea-94cc-707fb0250a9a.png width=600 />
+</div>