doc: add triagers to the table of contents

PR-URL: #39969
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

README.md

@@ -34,6 +34,7 @@ The Node.js project uses an [open governance model](./GOVERNANCE.md). The
 * [Current project team members](#current-project-team-members)
   * [TSC (Technical Steering Committee)](#tsc-technical-steering-committee)
   * [Collaborators](#collaborators)
+  * [Triagers](#triagers)
   * [Release keys](#release-keys)
 * [License](#license)