doc: fix typo "director" instead of "directory"

Change fs.readdirSync() description from "Reads the contents of
the director." to "Reads the contents of the directory."

PR-URL: https://github.com/nodejs/node/pull/37523


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Harshitha K P <harshitha014@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: James M Snell <jasnell@gmail.com>