Revise SECURITY.md for supported versions and reporting

Updated the security policy to reflect supported versions and vulnerability reporting process.

Author: julienld

SECURITY.md

@@ -0,0 +1,14 @@
+# Security Policy
+
+## Supported Versions
+
+| Version | Supported          |
+| ------- | ------------------ |
+| latest  | :white_check_mark: |
+
+
+## Reporting a Vulnerability
+
+Use the page at https://github.com/homeassistant-ai/ha-mcp/security/
+
+Will be assesed within 48h. Fix might take 24-48h.