Add link to README.

README.md

@@ -14,6 +14,10 @@
 [download-image]: https://img.shields.io/npm/dm/casbin.svg?style=flat-square
 [download-url]: https://npmjs.org/package/casbin
 
+💖 [**Looking for an open-source identity and access management solution like Okta, Auth0, Keycloak ? Learn more about: Casdoor**](https://casdoor.org/)
+
+<a href="https://casdoor.org/"><img src="https://user-images.githubusercontent.com/3787410/147868267-6ac74908-5654-4f9c-ac79-8852af9ff925.png" alt="casdoor" style="width: 50%; height: 50%"/></a>
+
 **News**: still worry about how to write the correct `node-casbin` policy? [Casbin online editor](http://casbin.org/en/editor) is coming to help!
 
 ![casbin Logo](casbin-logo.png)