Include information about security issues in README.md and

ISSUE_TEMPLATE.md

Author: tegon

ISSUE_TEMPLATE.md

@@ -2,6 +2,7 @@
 
 - Do not use the issues tracker for help or support, try Stack Overflow.
 - For bugs, do a quick search and make sure the bug has not yet been reported
+- If you found a security bug, do not report it through GitHub. Please send an e-mail to opensource@plataformatec.com.br instead.
 - Finally, be nice and have fun!
 
 ## Environment

README.md

@@ -1233,6 +1233,8 @@ sending us a pull request.
 
 https://github.com/plataformatec/simple_form/issues
 
+If you have discovered a security related bug, please do NOT use the GitHub issue tracker. Send an e-mail to opensource@plataformatec.com.br.
+
 ## Maintainers
 
 * José Valim (https://github.com/josevalim)