Revise security vulnerability reporting instructions

fix #113

Author: aeberhart

SECURITY.md

@@ -0,0 +1,19 @@
+# Security Policy
+
+## Reporting a Vulnerability
+
+Please do **not** report security vulnerabilities via public GitHub issues.
+
+Instead, report them by:
+- Emailing: info@dashjoin.com
+
+Please include:
+- affected version
+- proof of concept or reproduction steps
+- impact assessment, if known
+
+We will acknowledge reports within 7 days and keep you informed of our progress.
+
+## Supported Versions
+
+The latest released version is supported for security fixes.