Add note about original artifact version

Author: jvanbruegge

README.md

@@ -1,8 +1,10 @@
-This is the artifact accompanying the paper:
+This is an updated version of the artifact accompanying the paper:
 
 Barendregt Convenes with Knaster and Tarski:
 Strong Rule Induction for Syntax with Bindings
 
+The orignally reviewed version can be found [here](https://github.com/jvanbruegge/binder_datatypes/tree/POPL25_v1.2).
+
 ### How To Run?
 
 The artifact contains the tool support for defining binding datatypes and proving strong rule