Update fs.md

[muzhaqi16]

I thought it was the same thing as well but unfortunately when I use require('fs/promises') I do receive an error message on my node environment but not if I use the second option.

Error: Cannot find module 'fs/promises'
Require stack:

My node version is v12.18.3

Originally posted by @muzhaqi16 in #35726 (comment)

[aduh95]

The current documentation is only true for Node.js 14+. For Node.js 12, please check out https://nodejs.org/docs/latest-v12.x/api/fs.html#fs_fs_promises_api

For info, here is the support table for those features:

Node.js version range	require('fs/promises')	require('fs').promises
v10.0.0	✅	❌
≥v10.1.0 <14.0.0	❌	✅
≥14.0.0	✅	✅

Maybe we could add an history section in the docs to clarify what support users can expect.