doc: update mailmap and AUTHORS

Based on their GitHub and other social media profiles as well as the
most recent of their authored commits, I suspect watson goes by "Thomas
Watson" and not the name currently listed in the .mailmap and AUTHORS
files. Update.

I'm doing this because it  helps avoid false positives in
`find-inactive-collaborators.mjs` which uses `git shortlog` which uses
`.mailmap`.

PR-URL: #39393
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

.mailmap

@@ -393,7 +393,7 @@ Surya Panikkal <surya.com@gmail.com> suryagh <surya.com@gmail.com>
 Taehee Kang <hugnosis@gmail.com> hugnosis <hugnosis@gmail.com>
 Tanuja-Sawant <f2013658@goa.bits-pilani.ac.in> <thinkbigtanu@gmail.com>
 Taylor Woll <taylor.woll@microsoft.com> taylor.woll <tawoll@ntdev.microsoft.com>
-Thomas Watson Steen <w@tson.dk> Thomas Watson <w@tson.dk>
+Thomas Watson <w@tson.dk>
 Timothy O. Peters <timotewpeters@gmail.com>
 Timur Shemsedinov <timur.shemsedinov@gmail.com> tshemsedinov <timur.shemsedinov@gmail.com>
 Ting Shao <ting.shao@intel.com>

AUTHORS

@@ -1168,7 +1168,7 @@ Yoshiya Hinosawa <stibium121@gmail.com>
 Syuhei Kobayashi <nanocloudx@gmail.com>
 YutamaKotaro <california.dreamin.never.die@gmail.com>
 MURAKAMI Masahiko <fossamagna2@gmail.com>
-Thomas Watson Steen <w@tson.dk>
+Thomas Watson <w@tson.dk>
 Daijiro Yamada <yamad@daiji.ro>
 Kelvin Jin <kelvinjin@google.com>
 Mitsuo Utano <utano320@gmail.com>