Add new email for Karl Williamson

Author: khwilliamson

.mailmap

@@ -504,6 +504,7 @@ Karen Etheridge <ether@cpan.org> Karen Etheridge <github@froods.org>
 Karl Williamson <khw@cpan.org> Karl <khw@karl.(none)>
 Karl Williamson <khw@cpan.org> karl williamson (via RT) <perlbug-followup@perl.org>
 Karl Williamson <khw@cpan.org> Karl Williamson <khw@khw-desktop.(none)>
+Karl Williamson <khw@cpan.org> Karl Williamson <perl@khwilliamson.com>
 Karl Williamson <khw@cpan.org> Karl Williamson <public@khwilliamson.com>
 Karl Williamson <khw@cpan.org> karl williamson <public@khwilliamson.com>
 Karthik Rajagopalan <rajagopa@pauline.schrodinger.com> Karthik Rajagopalan <rajagopa@schrodinger.com>