Update README IDP migration warning (#406)

Author: joaopalet

README.md

@@ -17,9 +17,9 @@ Your feedback is appreciated!
 <a name="warning-new-stackit-idp"></a>
 
 > [!WARNING]
-> Starting on July 9 2024, the new [STACKIT Identity Provider (IDP)](https://docs.stackit.cloud/stackit/en/release-notes-23101442.html#ReleaseNotes-2024-06-21-identity-provider) will be available.
+> On July 9 2024, the new [STACKIT Identity Provider (IDP)](https://docs.stackit.cloud/stackit/en/release-notes-23101442.html#ReleaseNotes-2024-06-21-identity-provider) was released. We are happy to announce that on [v0.9.0](https://github.com/stackitcloud/stackit-cli/releases/tag/v0.9.0), the new IDP was integrated in the STACKIT CLI, where it is used for user authentication.
 >
-> On this date, we will release a new version of the STACKIT CLI that will use the new IDP for user authentication. This also means that the **user authentication on STACKIT CLI versions released before July 9 2024 is no longer guaranteed to work for all services**.
+> This also means that the **user authentication on STACKIT CLI versions released before July 9 2024 is no longer guaranteed to work for all services**.
 >
 > Please make sure to **update your STACKIT CLI to the latest version after July 9 2024** to ensure that you can continue to use all STACKIT services.