Update AUTHORS.txt.

Author: scottgonzalez

AUTHORS.txt

@@ -170,7 +170,7 @@ Ian Simpson <spoonlikesham@gmail.com>
 Lev Kitsis <spam4lev@gmail.com>
 TJ VanToll <tj.vantoll@gmail.com>
 Justin Domnitz <jdomnitz@gmail.com>
-Douglas Cerna <replaceafill@system76.(none)>
+Douglas Cerna <douglascerna@yahoo.com>
 Bert ter Heide <bertjh@hotmail.com>
 Jasvir Nagra <jasvir@gmail.com>
 Petr Hromadko <yuriy@tokyoscale.com>