Update Security Guidelines

Author: pitbulk

README.md

@@ -33,7 +33,7 @@ Update ``python3-saml`` to ``>= 1.2.1``, ``1.2.0`` had a bug on signature valida
 
 #### Security Guidelines ####
 
-If you believe you have discovered a security vulnerability in this toolkit, please report it in an issue with a description. We follow responsible disclosure guidelines, and will work with you to quickly find a resolution.
+If you believe you have discovered a security vulnerability in this gem, please report it by mail to the maintainer: sixto.martin.garcia+security@gmail.com
 
 Why add SAML support to my software?
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