doc: remove superfluous await from fsPromises.readdir example

The `await` operator in the example, iterating over the returned array
of filenames is not necessary, since the returned array is either
consisting of `string`s or of `fs.Dirent` objects, neither providing
an asyncIterator.

Refs: nodejs/help#3317

PR-URL: #38293
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

doc/api/fs.md

@@ -932,7 +932,7 @@ import { readdir } from 'fs/promises';
 
 try {
   const files = await readdir(path);
-  for await (const file of files)
+  for (const file of files)
     console.log(file);
 } catch (err) {
   console.error(err);