Create SECURITY.md for security policy

Added a security policy document outlining supported versions, vulnerability reporting, and responsible disclosure.

Author: Namitjain07

SECURITY.md

@@ -0,0 +1,21 @@
+# Security Policy
+
+## Supported Versions
+Only the latest version of the PrivacyFirst app and backend is actively supported.
+
+## Reporting a Vulnerability
+If you discover a security vulnerability:
+
+- **Do NOT open a public GitHub issue.**
+- Contact the maintainer directly:
+  - **Email:** your-email@example.com
+
+Please include:
+- Steps to reproduce
+- Potential impact
+- Suggested fix (if any)
+
+We take security seriously and will respond promptly.
+
+## Responsible Disclosure
+Please give us reasonable time to address vulnerabilities before public disclosure.