doc: add nodejs/tweet issue creation to sec. doc

This commit adds a suggestion to create a github issue for the security
release tweets. Currently, the security release document requests that
these tweets be created by asking in the #nodejs-social channel. Someone
from that channel would then create an issue, so we could just create
the issue ourselves.

PR-URL: https://github.com/nodejs/node/pull/39940


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>