docs: documentation files updated

SECURITY.md

@@ -1,3 +1,20 @@
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+# Security Policy
+
+## Supported Versions
+
+Only the the latest version of this project is supported at a given time. If
+you find a security issue with an older version, please try updating to the
+latest version first.
+
+If for some reason you can't update to the latest version, please let us know
+your reasons so that we can have a better understanding of your situation.
+
+## Reporting a Vulnerability
+
+For security inquiries or vulnerability reports, visit
+<https://thoughtbot.com/security>.
+
+If you have any suggestions to improve this policy, visit <https://thoughtbot.com/security>.
 
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