Update README.md

README.md

@@ -136,7 +136,7 @@ Via the easy-to-use, efficient, flexible and scalable implementation, our vision
 If you are in China, we recommend you to join our WeChat group to contact directly with our team members!
 
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-<img src="./docs/images/wechat_group.png"  width = "200"  />
+<img src="./docs/images/wechat_group.png"  width = "400"  />
 
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