[gnome-documents] sharing: add a link to the original JS email validator

[Cosimo Cecchi <cosimoc src gnome org>]

commit 65f84e2a2f8999c5d17b4d1ebd7e20d8d49de9a0
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Tue Jul 16 13:10:59 2013 -0700

    sharing: add a link to the original JS email validator
    
    And clarify the copyright/license for that piece of code.

 src/sharing.js |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)
---
diff --git a/src/sharing.js b/src/sharing.js
index 1fc938b..4f9fe32 100644
--- a/src/sharing.js
+++ b/src/sharing.js
@@ -1,6 +1,12 @@
 /*
  * Copyright(c) 2012 Meg Ford
- * Except for Line 530:
+ *
+ * Except for _isValidEmail(), adapted from:
+ * http://rosskendall.com/files/rfc822validemail.js.txt
+ * with GPLv2+ license and the following copyright header.
+ *
+ * ====
+ *
  * JavaScript function to check an email address conforms to RFC822 (http://www.ietf.org/rfc/rfc0822.txt)
  *
  * Version: 0.2
@@ -13,6 +19,8 @@
  * Portions copyright (C) 2006  Ross Kendall - http://rosskendall.com
  * Portions copyright (C) 1993-2005 Cal Henderson - http://iamcal.com
  *
+ * ====
+ *
  * Gnome Documents is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by the
  * Free Software Foundation; either version 2 of the License, or (at your