doc: fix small typo in 15.11.0 release

PR-URL: https://github.com/nodejs/node/pull/37590


Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>