Update AUTHORS.md

Author: simongravelle

AUTHORS.md

@@ -1,10 +1,10 @@
 ## Authors
 
-- [Simon Gravelle](https://github.com/simongravelle) (corresponding author),
-  Univ. Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France
+- [Simon Gravelle](https://github.com/simongravelle) (corr. author),
+  Université Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France.
 - [Jacob R. Gissinger](https://www.stevens.edu/profile/jgissing),
-  Stevens Institute of Technology, Hoboken, NJ 07030, USA
+  Stevens Institute of Technology, Hoboken, NJ 07030, USA.
 - [Axel Kohlmeyer](https://sites.google.com/site/akohlmey),
   Institute for Computational Molecular Science, Temple University, Philadelphia,
-  PA 19122, USA
+  PA 19122, USA.