tools: enable no-useless-return eslint rule

PR-URL: https://github.com/nodejs/node/pull/12577
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

doc/api/errors.md

@@ -64,6 +64,7 @@ Errors that occur within _Asynchronous APIs_ may be reported in multiple ways:
   argument is not `null` and is an instance of `Error`, then an error occurred
   that should be handled.
 
+<!-- eslint-disable no-useless-return -->
   ```js
   const fs = require('fs');
   fs.readFile('a file that does not exist', (err, data) => {