docs: update readme shields

Author: rdnfn

README.rst

@@ -16,13 +16,14 @@
 .. image:: https://img.shields.io/pypi/v/beobench.svg
         :target: https://pypi.python.org/pypi/beobench
 
-.. image:: https://img.shields.io/travis/rdnfn/beobench.svg
-        :target: https://travis-ci.com/rdnfn/beobench
-
 .. image:: https://readthedocs.org/projects/beobench/badge/?version=latest
         :target: https://beobench.readthedocs.io/en/latest/?version=latest
         :alt: Documentation Status
 
+.. image:: https://img.shields.io/badge/License-MIT-blue.svg
+        :target: https://opensource.org/licenses/MIT
+        :alt: License
+
 A toolbox for benchmarking reinforcement learning (RL) algorithms on building energy optimisation (BEO) problems. Beobench does not replace existing libraries defining BEO problems (such as `BOPTEST <https://github.com/ibpsa/project1-boptest>`_) — instead it makes working with them easier.
 
 Features