doc: remove typo in crypto.md

Change "its[sic] recommended to" to "be sure to". This fixes a typo and
also improves the passive and indirect phrasing to a more concise active
and direct phrasing.

PR-URL: https://github.com/nodejs/node/pull/34698


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>