Update AUTHORS.md

AUTHORS.md

+This file lists the authors of the WEST code as well as the known contributors.
+
 # Project Leads 
 
 - Marco Govoni (Argonne National Laboratory and University of Chicago)
 - Giulia Galli (University of Chicago and Argonne National Laboratory)
 
-## Developers
+# Developers
+
+The current list of developers, in alphabetical order:
 
 - Sijia Dong (Argonne National Laboratory)
 - Marco Govoni (Argonne National Laboratory and University of Chicago)
 - He Ma (University of Chicago)
 - Han Yang (University of Chicago)
 
-## Contributors
+# Former Developers
+
+The former list of developers, in alphabetical order:
+
+- Nicholas Brawand (2016-2018)
+- Matteo Gerosa (2017-2018)
+- Ryan McAvoy (2017-2018)
+- Ngoc Linh Nguyen (2017-2018)
+- Peter Scherpelz (2016-2017)
+- Feng Wu (2018)
+- Huihuo Zheng (2016-2018)
+
+# Contributors
 
-- Francois Gygi (University of California, Davis)
-- Ikutaro Hamada (Osaka University)
-- Yuan Ping (University of California, Santa Cruz)
-- Jonathan Skone (University of Chicago)
-- Tyler Smart (University of California, Santa Cruz)
-- Aditya Tanikanti (University of Chicago)
+We would like to thank the following people for their contibution (beside generic comments and bugfixes):
 
-## Former Developers
+- Francois Gygi (University of California, Davis): for strategic discussions
+- Ikutaro Hamada (Osaka University): for the first implementation of k-points
+- Yuan Ping (University of California, Santa Cruz): for 2D cutoff
+- Jonathan Skone (University of Chicago): hybrid functionals
+- Tyler Smart (University of California, Santa Cruz): for 2D cutoff
+- Aditya Tanikanti (University of Chicago): for deployment and testing
 
-- Nicholas Brawand
-- Matteo Gerosa 
-- Ryan McAvoy
-- Ngoc Linh Nguyen
-- Peter Scherpelz
-- Feng Wu 
-- Huihuo Zheng 
+Please, don't hesitate to contact us if you see that information is wrong or missing in this file.