Add deprecation warning in warning and docs

Author: DavidWalz

README.md

@@ -4,6 +4,7 @@
 [![Docs](https://github.com/basf/mopti/actions/workflows/docs.yml/badge.svg)](https://basf.github.io/mopti/)
 [![PyPI](https://img.shields.io/pypi/v/mopti.svg?color=%2334D058)](https://pypi.org/project/mopti)
 
+**Opti is deprecated. Consider using [BoFire](https://github.com/experimental-design/bofire) instead.**
 
 Opti is a Python package for specifying problems in a number of closely related fields, including experimental design, multiobjective optimization, decision making and Bayesian optimization.
 

docs/index.md

@@ -1,5 +1,8 @@
 # Introduction
 
+!!! warning
+    Opti is deprecated. Consider using [BoFire](https://github.com/experimental-design/bofire) instead.
+
 The primary purpose of opti is to define tasks or problems in a number of closely related fields, including experimental design, multiobjective optimization and decision making and Bayesian optimization.
 
 Opti specifications are json serializable for use in RESTful APIs and are to a large extent agnostic to the specific methods and frameworks in which the problems are solved.