update paper doi

revision of paper has been published so we update to it

Author: agoscinski

README.rst

@@ -113,4 +113,4 @@ Thanks goes to all people that make scikit-matter possible:
 
 .. |doi| image:: https://img.shields.io/badge/DOI-10.12688-blue
    :alt: ORE Paper
-   :target: https://doi.org/10.12688/openreseurope.15789.1
+   :target: https://doi.org/10.12688/openreseurope.15789.2