doc: replace function with arrow function in vm.md

PR-URL: #17307
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: Yosuke Furukawa <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Daijiro Wachi <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Jon Moss <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: narirou

doc/api/vm.md

@@ -474,7 +474,7 @@ to the `http` module passed to it. For instance:
 const vm = require('vm');
 
 const code = `
-(function(require) {
+((require) => {
   const http = require('http');
 
   http.createServer((request, response) => {