Add security policy link to readme

Author: per1234

README.md

@@ -180,6 +180,14 @@ QUIT
 $
 ```
 
+## Security
+
+If you think you found a vulnerability or other security-related bug in this project, please read our
+[security policy](https://github.com/arduino/serial-discovery/security/policy) and report the bug to our Security Team 🛡️
+Thank you!
+
+e-mail contact: [email protected]
+
 ## License
 
 Copyright (c) 2018 ARDUINO SA (www.arduino.cc)