Update README.md

Direct folks to foss repository

Author: damianh

README.md

@@ -1,4 +1,8 @@
 ## About Duende.AccessTokenManagement
+
+> [!IMPORTANT]  
+> This project is now managed in our [FOSS repository](https://github.com/DuendeSoftware/foss/tree/main/access-token-management).
+
 This is the repository for a set of .NET libraries that manage OAuth and OpenId
 Connect access tokens. These tools automatically acquire new tokens when old
 tokens are about to expire, provide conveniences for using the current token
@@ -22,4 +26,4 @@ Duende.AccessTokenManagement is released as open source under the
 [Bug reports, feature requests](https://github.com/DuendeSoftware/Duende.AccessTokenManagement/issues) and 
 [contributions](https://github.com/DuendeSoftware/Duende.AccessTokenManagement/pulls) are welcome. 
 If you have an idea for a new feature or significant code change you'd like to propose, please start with a 
-GitHub issue so that we can discuss it. Thanks in advance!
+GitHub issue so that we can discuss it. Thanks in advance!