doc: add TimothyGu to collaborators

PR-URL: #10954
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: TimothyGu

README.md

@@ -329,6 +329,8 @@ more information about the governance of the Node.js project, see
 **Glen Keane** <glenkeane.94@gmail.com>
 * [thlorenz](https://github.com/thlorenz) -
 **Thorsten Lorenz** <thlorenz@gmx.de>
+* [TimothyGu](https://github.com/TimothyGu) -
+**Timothy Gu** <timothygu99@gmail.com>
 * [tunniclm](https://github.com/tunniclm) -
 **Mike Tunnicliffe** <m.j.tunnicliffe@gmail.com>
 * [vkurchatkin](https://github.com/vkurchatkin) -