Update notebook notification image.

Author: mwakaba2

README.md

@@ -7,7 +7,7 @@
 
 Notebook Cell Completion Browser Notifications for JupyterLab. 
 
-<img width="398" alt="notification" src="https://user-images.githubusercontent.com/3497137/111880929-2be04480-897c-11eb-8655-7e6702d70d87.png">
+<img width="387" alt="notification" src="https://user-images.githubusercontent.com/3497137/118382531-3275eb80-b5bc-11eb-9810-5b92183609c3.png">
 
 
 ## Requirements