Add security policy

Copied from cilium/cilium security policy.

Signed-off-by: Nicolas Busseneau <[email protected]>

SECURITY.md

@@ -0,0 +1,10 @@
+# Security Policy
+
+## Reporting a Vulnerability
+
+We strongly encourage you to report security vulnerabilities to
+our private security mailing list: [email protected] - first, before
+disclosing them in any public forums.
+
+This is a private mailing list where only members of the Cilium internal
+security team are subscribed to, and is treated as top priority.