doc: Format security advisory titles and headings

Required so that the advisory documents are all valid RST files (with a
header) and that they all integrate into the document tree.

Change-Id: I68ca2b0b9e648e24b460deb772c471a38518da26
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/security_advisories/security-advisory-tfv-4.rst b/docs/security_advisories/security-advisory-tfv-4.rst
index 386d0da..66dd542 100644
--- a/docs/security_advisories/security-advisory-tfv-4.rst
+++ b/docs/security_advisories/security-advisory-tfv-4.rst
@@ -1,3 +1,6 @@
+Advisory TFV-4 (CVE-2017-9607)
+==============================
+
 +----------------+-------------------------------------------------------------+
 | Title          | Malformed Firmware Update SMC can result in copy or         |
 |                | authentication of unexpected data in secure memory in       |