doc: update abort signal in fs promise api example

PR-URL: #38669
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

doc/api/fs.md

@@ -984,12 +984,15 @@ import { readFile } from 'fs/promises';
 
 try {
   const controller = new AbortController();
-  const signal = controller.signal;
-  readFile(fileName, { signal });
+  const { signal } = controller;
+  const promise = readFile(fileName, { signal });
 
-  // Abort the request
+  // Abort the request before the promise settles.
   controller.abort();
+
+  await promise;
 } catch (err) {
+  // When a request is aborted - err is an AbortError
   console.error(err);
 }
 ```
@@ -1003,7 +1006,6 @@ Any specified {FileHandle} has to support reading.
 <!-- YAML
 added: v10.0.0
 -->
-
 * `path` {string|Buffer|URL}
 * `options` {string|Object}
   * `encoding` {string} **Default:** `'utf8'`
@@ -1309,8 +1311,12 @@ try {
   const controller = new AbortController();
   const { signal } = controller;
   const data = new Uint8Array(Buffer.from('Hello Node.js'));
-  writeFile('message.txt', data, { signal });
+  const promise = writeFile('message.txt', data, { signal });
+
+  // Abort the request before the promise settles.
   controller.abort();
+
+  await promise;
 } catch (err) {
   // When a request is aborted - err is an AbortError
   console.error(err);