docs(security): security advisory for CVE-2024-5660

Add CVE-2024-5660 security advisory document.

Change-Id: I0d0428061f60b6fe83d03362b27b960f6ddcc6f4
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/docs/security_advisories/index.rst b/docs/security_advisories/index.rst
index ad55546..0ab73bc 100644
--- a/docs/security_advisories/index.rst
+++ b/docs/security_advisories/index.rst
@@ -16,3 +16,4 @@
    security-advisory-tfv-9.rst
    security-advisory-tfv-10.rst
    security-advisory-tfv-11.rst
+   security-advisory-tfv-12.rst