doc: deprecate (doc-only) crypto.Certificate()

Documentation-only: Recommend people use the static methods on
crypto.Certificate() and not the legacy API constructor.

PR-URL: https://github.com/nodejs/node/pull/34697


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ujjwal Sharma <ryzokuken@disroot.org>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>