Put a link to the Github contributors list

AUTHORS.md

@@ -1,4 +1,7 @@
-If you contribute time, code or resources to the project, feel free to add
-your name, pseudonym, and any contact information you feel relevant.
+Most contributors are listed on Github at:
 
-- kaiyou
+ https://github.com/kaiyou/freeposte.io/graphs/contributors
+
+If you contribute time, code or resources to the project, feel free to add
+your name, pseudonym, and any contact information you feel is relevant to
+this file.