Update citation

README.md

@@ -75,12 +75,11 @@ This software is distributed under the [MIT Licence](https://mit-license.org).
 If you use this package for your own work, please consider citing it as :
 
 ```bibtex
-@misc{guyard2021screen,
-      title={Screen & Relax: Accelerating the resolution of Elastic-net by safe identification of the solution support}, 
-      author={Théo Guyard and Cédric Herzet and Clément Elvira},
-      year={2021},
-      eprint={2110.07281},
-      archivePrefix={arXiv},
-      primaryClass={math.OC}
+@article{guyard2021screen,
+  title={Screen \& Relax: Accelerating the resolution of Elastic-net by safe identification of the solution support},
+  author={Guyard, Th{\'e}o and Herzet, C{\'e}dric and Elvira, Cl{\'e}ment},
+  journal={arXiv preprint arXiv:2110.07281},
+  year={2021}
 }
+
 ```