Add Swell provider (#1081)

Author: maarten2424

README.md

@@ -27,6 +27,7 @@ Vercel is more than happy to partner and work with any commerce provider to help
 - [BigCommerce](https://github.com/bigcommerce/nextjs-commerce) ([Demo](https://next-commerce-v2.vercel.app/))
 - [Medusa](https://github.com/medusajs/vercel-commerce) ([Demo](https://medusa-nextjs-commerce.vercel.app/))
 - [Saleor](https://github.com/saleor/nextjs-commerce) ([Demo](https://saleor-commerce.vercel.app/))
+- [Swell](https://github.com/swellstores/verswell-commerce) ([Demo](https://verswell-commerce.vercel.app/))
 
 ## Running locally