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-3.rst b/docs/security_advisories/security-advisory-tfv-3.rst
index 28e10bf..f74ef17 100644
--- a/docs/security_advisories/security-advisory-tfv-3.rst
+++ b/docs/security_advisories/security-advisory-tfv-3.rst
@@ -1,3 +1,6 @@
+Advisory TFV-3 (CVE-2017-7563)
+==============================
+
 +----------------+-------------------------------------------------------------+
 | Title          | RO memory is always executable at AArch64 Secure EL1        |
 +================+=============================================================+