Update README.md

Author: shtnkgm

README.md

@@ -12,7 +12,7 @@ Something looks like below:
 
 |e.g. UIImageView|e.g. UIImageView in UICollectionView|
 |:---:|:---:|
-|<img src="https://github.com/shtnkgm/ImageTransition/raw/master/docs/assets/sample_01.gif" alt="Sample" width="200px" /> | <img src="https://github.com/shtnkgm/ImageTransition/raw/master/docs/assets/sample_02.gif" alt="Sample" width="200px" />|
+|<img src="https://github.com/shtnkgm/ImageTransition/raw/master/docs/assets/sample_01.gif" alt="sample_01.gif" width="200px" /> | <img src="https://github.com/shtnkgm/ImageTransition/raw/master/docs/assets/sample_02.gif" alt="sample_02.gif" width="200px" />|
 
 ## Feature
  - [x] Transition zooming animation like the iOS Photos app and the "Pinterest", and so on