Merge branch 'readme-security' into MAGETWO-50222-PRs

Author: Eddie Lau

Diff for: README.md

@@ -72,3 +72,10 @@ To suggest documentation improvements, click [here][4].
 [2]: <http://devdocs.magento.com/guides/v2.0/contributor-guide/contributing.html#report>
 [3]: <https://github.com/magento/magento2/issues>
 [4]: <http://devdocs.magento.com>
+
+<h2>Reporting security issues</h2>
+
+To report security vulnerabilities in Magento software or web sites, please email <a href="mailto:security@magento.com">security@magento.com</a>. Please do not report security issues through GitHub. Be sure to encrypt your email with our <a href="https://info2.magento.com/rs/magentoenterprise/images/security_at_magento.asc">encryption key</a> if it includes sensitive info. Learn more about reporting security issues <a href="https://magento.com/security/reporting-magento-security-issue">here</a>.
+
+Stay up to date on the latest vulnerabilities and patches for Magento by signing up for <a href="https://magento.com/security/sign-up">Security Alert Notifications</a>.
+