Add my former address to .mailmap

.mailmap

@@ -324,6 +324,7 @@ Katze <binary@benary.org>
 Keegan McAllister <mcallister.keegan@gmail.com> <kmcallister@mozilla.com>
 Kerem Kat <keremkat@gmail.com>
 Kevin Butler <haqkrs@gmail.com>
+Kevin Reid <kpreid@switchb.org> <kpreid@google.com>
 Kevin Jiang <kwj2104@columbia.edu>
 Kornel Lesiński <kornel@geekhood.net>
 Krishna Sai Veera Reddy <veerareddy@email.arizona.edu>