doc: use top-level await syntax in vm.md

[aduh95]

TLA allows us to use more concise example and get rid of IIFE async functions.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/35773/

[Trott]

This would change the examples to be ones that cannot be placed in a .js file (let's say index.js) and run as node index.js. To me, that's a pretty big change and one we'd want to sort out across the docs. But maybe I'm wrong. @nodejs/documentation

[aduh95]

Removed author ready label to try to get more opinions before landing. I've also opened #37162 to address the more general issue.

[jasnell]

Landed in 2be512d