Update AUTHORS.txt

Author: Sean-Der

AUTHORS.txt

@@ -18,6 +18,7 @@ lllf <littlelightlittlefire@gmail.com>
 Luke Curley <kixelated@gmail.com>
 Mathis Engelbart <mathis.engelbart@gmail.com>
 Max Hawkins <maxhawkins@gmail.com>
+Sean <sean@siobud.com>
 Sean DuBois <seaduboi@amazon.com>
 Sean DuBois <sean@siobud.com>
 Simone Gotti <simone.gotti@gmail.com>