doc: clarify v0.10.41 openssl tls security impact

Updated to match the amended description that went live on the release
announcement @ http://nodejs.org/en/blog/release/v0.10.41/

PR-URL: https://github.com/nodejs/node/pull/4153


Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Minwoo Jung <jmwsoft@gmail.com>