doc: fix an error in resolution algorithm steps

As it is, if `X begins with './' or '/' or '../'` (step 3), it reads
as if it were possible for the algorithm to do a node_modules lookup
(step 4). But that doesn't seem to reflect the actual logic.

PR-URL: https://github.com/nodejs/node/pull/29940


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>