doc: replace function with arrow function in vm.md

PR-URL: #17307
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Yosuke Furukawa <yosuke.furukawa@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: narirou

doc/api/vm.md

@@ -458,7 +458,7 @@ to the `http` module passed to it. For instance:
 const vm = require('vm');
 
 const code =
-`(function(require) {
+`((require) => {
 
    const http = require('http');