Add link to README.

Author: hsluoyz

README.md

@@ -6,6 +6,10 @@ Casbin-CPP
 [![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg)](https://github.com/semantic-release/semantic-release)
 [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/casbin/lobby)
 
+💖 [**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**: Are you still worried about how to write the correct Casbin policy? ``Casbin online editor`` is coming to help! Try it at: http://casbin.org/editor/
 
 ## Build Availability on Platforms: