Update README.md

Author: bertiqwerty

README.md

@@ -19,4 +19,7 @@ Opti ...
 * json-serializes problems for use in RESTful APIs and json/bson DBs, and
 * provides a range of benchmark problems for (multi-objective) optimization and Bayesian optimization.
 
-**Note:** We are developing a successor of opti called [BoFire](https://github.com/experimental-design/bofire).
+## BoFire
+
+We are developing a successor of opti called [BoFire](https://github.com/experimental-design/bofire) and recommend using that. To help you
+with the transition to BoFire there is https://github.com/experimental-design/bofire-converters.