doc: correct EventEmitter reference

PR-URL: https://github.com/nodejs/node/pull/16791
Fixes: https://github.com/nodejs/node/issues/16789


Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>