add link to security from contributing to readme

Author: Michael Marti

README.md

@@ -7,6 +7,10 @@ Be sure to:
 * Change the title in this README
 * Edit your repository description on GitHub
 
+## Security
+
+See [CONTRIBUTING](CONTRIBUTING.md#security-issue-notifications) for more information.
+
 ## License
 
 This library is licensed under the MIT-0 License. See the LICENSE file.