Update README.md

lizhuoyuan · web-flow · commit b1843b637a8b · 2020-07-28T15:27:12.000+08:00
diff --git a/README.md b/README.md
@@ -15,7 +15,7 @@
 [Update log](https://github.com/OpenFlutter/flutter_screenutil/blob/master/CHANGELOG.md)
 
 ## Note
-v3 requires `flutter >= 1.19.0`. 
+![v3](https://github.com/OpenFlutter/flutter_screenutil/tree/beta) requires `flutter >= 1.19.0`. 
 v2 for current stable version of flutter.
 
 ## Usage:
