doc: remove unnecessary "obvious(ly)" modifiers in esm.md

Remove "obvious" and "obviously" in two places in esm.md. It may be
obvious to some, but likely not everyone or else it probably wouldn't be
worth mentioning/documenting.

PR-URL: https://github.com/nodejs/node/pull/32457


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>