doc: fix example of crypto.generateKeySync

doc: fix the example of crypto.generateKeySync

The "options" argument must be an object.

PR-URL: https://github.com/nodejs/node/pull/40225


Reviewed-By: Qingyu Deng <i@ayase-lab.com>
Reviewed-By: Harshitha K P <harshitha014@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>