async_hooks: fix imports in context example

Added imports for packages that is mentioned in the example of async_hooks context example. PR-URL: #39229 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Gerhard Stöbich <[email protected]>

Author: yashLadha

doc/api/async_hooks.md

@@ -433,6 +433,9 @@ callback to `listen()` will look like. The output formatting is slightly more
 elaborate to make calling context easier to see.
 
 ```js
+constasync_hooks=require('async_hooks');
+constfs=require('fs');
+constnet=require('net');
 const{fd } =process.stdout;
 
 let indent =0;