Update link to citation file in README.rst

Author: LacombeLouis

README.rst

@@ -229,4 +229,4 @@ MAPIE is free and open-source software licensed under the `3-clause BSD license
 📚 Citation
 ===========
 
-If you use MAPIE in your research, please cite using `citations file <CITATION.CFF>`_ on our repository.
+If you use MAPIE in your research, please cite using `citations file <CITATION.cff>`_ on our repository.