Revise security policy and reporting guidelines (#4550)

Author: qxyuan853

SECURITY.md

@@ -0,0 +1,15 @@
+# Security Policy
+
+## Supported Versions
+
+Only the latest stable version of dinky receives security updates. Make sure you are running the most recent release.
+
+
+## Reporting a Vulnerability
+
+Please do not open public issues for security problems. Instead, use GitHub's "Report a vulnerability" feature in the Security tab of this repository. 
+We will review and respond as soon as possible.
+
+## Security Updates
+
+If we fix a vulnerability, we will announce it in the release notes. Keep your installation up to date to receive the latest fixes.