Added Vercel OSS badge

Author: rajat1saxena

docs/README.md

@@ -133,3 +133,8 @@ npm i mongoose nanoid
 ```
 DB_CONNECTION_STRING=mongodb://<mongodb-url> node migration-script.js
 ```
+
+## Supported By
+<a href="https://vercel.com/oss">
+  <img alt="Vercel OSS Program" src="https://vercel.com/oss/program-badge.svg" />
+</a>