Add Peter Williams to AUTHORS

Author: catamorphism

AUTHORS.txt

@@ -108,6 +108,7 @@ Patrik Kårlin <patrik.karlin@gmail.com>
 Paul Stansifer <paul.stansifer@gmail.com>
 Paul Woolcock <pwoolcoc+github@gmail.com>
 Peter Hull <peterhull90@gmail.com>
+Peter Williams <peter@newton.cx>
 Philipp Brüschweiler <blei42@gmail.com>
 Rafael Ávila de Espíndola <respindola@mozilla.com>
 Ralph Giles <giles@thaumas.net>