Feat: Add a link to a working express application

I've just made an express app with stackblitz.
It can also be used as a starter template 😉
The main goal here is to add ExpressJs to the list of supported frameworks.

Author: Davien21

Supported_frameworks.md

@@ -4,6 +4,7 @@ The following is a list of frameworks that we have actively tested and are suppo
 
 - [Next.js](https://stackblitz.com/fork/nextjs)
 - [NestJS](https://stackblitz.com/fork/nestjs-starter)
+- [ExpressJS](https://stackblitz.com/edit/expressjs)
 
 ## Add support for a framework