add gif

README.md

@@ -3,6 +3,10 @@
 We should know that in order to achieve Gif in flutter, we can use Image, but we have no way to manipulate Gif, for example: change its speed, control it has been playing in a frame,
  in which frame range loop. These problems can be solved by this widget,it also help you contain gif cache,avoid load frame every time.
 
+# Screenshots
+
+![](arts/gif.gif)
+
 # Usage(Simple)
 
  ```dart