doc: update output of example in AbortController

Actual output of example in AbortController is mismatched.
Plus, make `reason` parameter as optional in JSDoc.

Refs: https://github.com/nodejs/node/blob/main/doc/api/globals.md#abortcontrollerabortreason
Refs: https://github.com/nodejs/node/blob/main/doc/api/globals.md#static-method-abortsignalabortreason
PR-URL: #47227
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>
Reviewed-By: Erick Wendel <erick.workspace@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/globals.md

@@ -43,7 +43,7 @@ ac.signal.addEventListener('abort', () => console.log('Aborted!'),
 
 ac.abort();
 
-console.log(ac.signal.aborted);  // Prints True
+console.log(ac.signal.aborted);  // Prints true
 ```
 
 ### `abortController.abort([reason])`
@@ -196,7 +196,7 @@ An optional reason specified when the `AbortSignal` was triggered.
 ```js
 const ac = new AbortController();
 ac.abort(new Error('boom!'));
-console.log(ac.signal.reason);  // Error('boom!');
+console.log(ac.signal.reason);  // Error: boom!
 ```
 
 #### `abortSignal.throwIfAborted()`

lib/internal/abort_controller.js

@@ -163,7 +163,7 @@ class AbortSignal extends EventTarget {
   }
 
   /**
-   * @param {any} reason
+   * @param {any} [reason]
    * @returns {AbortSignal}
    */
   static abort(
@@ -337,7 +337,7 @@ class AbortController {
   }
 
   /**
-   * @param {any} reason
+   * @param {any} [reason]
    */
   abort(reason = new DOMException('This operation was aborted', 'AbortError')) {
     validateAbortController(this);