doc: update mailmap entries for mhdawson

Update the content and order of my mailmap entries. Recent
changelogs have been using my outdated email address.

Signed-off-by: Michael Dawson <mdawson@devrus.com>

PR-URL: nodejs#41437
Reviewed-By: Tierney Cyren <hello@bnb.im>
Reviewed-By: Adrian Estrada <edsadr@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Derek Lewis <DerekNonGeneric@inf.is>
Reviewed-By: Rich Trott <rtrott@gmail.com>

Author: mhdawson

.mailmap

@@ -323,7 +323,8 @@ Matthias Bastian <dev@matthias-bastian.de> <piepmatz@users.noreply.github.com>
 Maurice Hayward <mauricehayward1@gmail.com>
 Maya Lekova <apokalyptra@gmail.com> <mslekova@chromium.org>
 Michael Bernstein <michaelrbernstein@gmail.com>
-Michael Dawson <michael_dawson@ca.ibm.com> <mdawson@devrus.com>
+Michael Dawson <midawson@redhat.com> <mdawson@devrus.com>
+Michael Dawson <midawson@redhat.com> <michael_dawson@ca.ibm.com>
 Michael Starzinger <mstarzinger@chromium.org>
 Michaël Zasso <targos@protonmail.com> <mic.besace@gmail.com>
 Michael-Rainabba Richardson <rainabba@gmail.com>