Add deprecation notice to README

Author: sbihel

README.md

@@ -1,3 +1,6 @@
+> [!IMPORTANT]
+> As we do not use the DIDKit bindings internally anymore, we have decided to archive their respective repositories. If you are looking for alternatives, our Rust library [`ssi`](https://github.com/spruceid/ssi/) (on which DIDKit was built) is still in active deployment, and we have new mobile-focused libraries with [`sprucekit-mobile`](https://github.com/spruceid/sprucekit-mobile). And as always, you are welcome to fork our repositories.
+
 [![PyPI version](https://badge.fury.io/py/didkit.svg)](https://badge.fury.io/py/didkit)
 
 Check out the DIDKit documentation [here](https://spruceid.dev/docs/didkit/).