doc: add Tobias to the TSC

refs: nodejs/TSC#746

PR-URL: #29545
Refs: nodejs/TSC#746
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

Author: mhdawson

README.md

@@ -184,6 +184,8 @@ For information about the governance of the Node.js project, see
 **Michaël Zasso** <targos@protonmail.com> (he/him)
 * [thefourtheye](https://github.com/thefourtheye) -
 **Sakthipriyan Vairamani** <thechargingvolcano@gmail.com> (he/him)
+* [tniessen](https://github.com/tniessen) -
+**Tobias Nießen** <tniessen@tnie.de>
 * [Trott](https://github.com/Trott) -
 **Rich Trott** <rtrott@gmail.com> (he/him)