doc: add clearer setup description

Updated console example to follow style of rest of the examples

PR-URL: https://github.com/nodejs/node/pull/15962


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>