Update AUTHORS.txt documentation

Author: magreenblatt

AUTHORS.txt

@@ -1,7 +1,8 @@
 # This file is an addendum to the Chromium Embedded Framework AUTHORS file. It
 # lists authors through March 18, 2015 when Git was introduced for source code
-# management. A list of authors after that date can be found by executing this
-# command on a local Git checkout: git log --all --format="%aN <%aE>" | sort -u
+# management. A list of additional authors added after that date can be found
+# by executing this command on a local Git checkout:
+# git log --all --format="%aN <%aE>" | sort -u
 
 Marshall Greenblatt <magreenblatt@gmail.com>
 Kai Klimke, censhare AG <kkl@censhare.com>