add contribution and citation in readme

README.org

@@ -74,6 +74,13 @@ cd snowlaps
 
 [[./data/assets/app_forward.png]]
 
+* Contributions
 
+Any contribution to =snowlaps= is welcome! Feel free to add new issues, open pull requests or ask questions in the discussion forum. 
 
+* Citation
+
+If you use this code, please cite the associated publication: 
+
+Chevrollier, L.-A., Wehrlé, A., Cook, J. M., Pirk, N., Benning, L. G., Anesio, A. M., and Tranter, M.: Separating the albedo reducing effect of different light absorbing particles on snow using deep learning, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2024-2583, 2024.