feat: adding sponsor banner (#317)

Author: hemanth

README.md

@@ -2,7 +2,8 @@
 
 > Useful resources for creating Progressive Web Apps
 
-_Inspired by the [awesome](https://github.com/sindresorhus/awesome) list thing._
+## Sponsors 
+![https://www.magicbell.com/](https://magicbell.notion.site/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fd0514836-68dc-4efa-864a-532932529baf%2FLogoMB_purple.svg?table=block&id=ca04cc4f-a5ff-4629-9614-13b705a27ae3&spaceId=747204a9-b3b5-4726-8379-1b04a63bafa6&userId=&cache=v2)
 
 ## What is a Progressive Web App
 
@@ -178,6 +179,7 @@ _Source:_ [Google Developers - Progressive Web Apps](https://developers.google.c
 * [Yahtzee](https://zpix1.github.io/yahtzee/): Dice generator.
 * [Youtube Music](https://music.youtube.com/): Music streaming via YouTube.
 * [ztable.io](https://ztable.io/): Z-Table lookup & Z-Score calculator.
+* [webpushtest](https://webpushtest.com/): Web Push Notifications Demo
 
 ## Tutorials