Update README.md

README.md

@@ -18,6 +18,7 @@ There are 3 steps in this tutorial.
 
 In this part, I'll show a example code of self-rotating 3d cube and a example output of it.\
 [https://git.ajou.ac.kr/Jiyoung_Moon/mouse-drag-for-transform-camera/-/raw/master/self-rotating-cube.gif](https://git.ajou.ac.kr/Jiyoung_Moon/mouse-drag-for-transform-camera/-/raw/master/self-rotating-cube.gif)\
+![self-rotating-cube](self-rotating-cube.gif)
 This code is used for the next steps.
 
 ## Step 1. Remove some codes.