shrink the size of images in README

Author: github-bowen

README.md

@@ -16,8 +16,8 @@ Then, run `app1.mlapp1` in MATLAB.
 
 ## UI Screenshots
 
-<img src="./img-in-readme/1.png" style="zoom:30%;" />
+<img src="./img-in-readme/1.png" width="500" height="400" />
 
-<img src="./img-in-readme/2.png" style="zoom:30%;" />
+<img src="./img-in-readme/2.png" width="500" height="400" />
 
-<img src="./img-in-readme/3.png" style="zoom:30%;" />
+<img src="./img-in-readme/3.png" width="500" height="400" />