doc: simplify addAbortListener example

The example was written before v8 supported the using keyword
and hence explicitly called Symbol.dispose

Since now the keyword is supported, the example can be simplified

PR-URL: #61842
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: atlowChemi

doc/api/events.md

@@ -1908,31 +1908,25 @@ Returns a disposable so that it may be unsubscribed from more easily.
 const { addAbortListener } = require('node:events');
 
 function example(signal) {
-  let disposable;
-  try {
-    signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
-    disposable = addAbortListener(signal, (e) => {
-      // Do something when signal is aborted.
-    });
-  } finally {
-    disposable?.[Symbol.dispose]();
-  }
+  signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
+  // addAbortListener() returns a disposable, so the `using` keyword ensures
+  // the abort listener is automatically removed when this scope exits.
+  using _ = addAbortListener(signal, (e) => {
+    // Do something when signal is aborted.
+  });
 }
 ```
 
 ```mjs
 import { addAbortListener } from 'node:events';
 
 function example(signal) {
-  let disposable;
-  try {
-    signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
-    disposable = addAbortListener(signal, (e) => {
-      // Do something when signal is aborted.
-    });
-  } finally {
-    disposable?.[Symbol.dispose]();
-  }
+  signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
+  // addAbortListener() returns a disposable, so the `using` keyword ensures
+  // the abort listener is automatically removed when this scope exits.
+  using _ = addAbortListener(signal, (e) => {
+    // Do something when signal is aborted.
+  });
 }
 ```