Docs: Manually set security advisory documents in order

Manually sort the security advisory documents in order.
Otherwise, rendered documents are sorted according to file names in
alphabetical order.

Change-Id: Ib49c788ae1e37c24ff84d44429ed3963d85c5267
Signed-off-by: David Hu <david.hu@arm.com>
diff --git a/docs/security/security_advisories/index.rst b/docs/security/security_advisories/index.rst
index 8511908..5f03f31 100644
--- a/docs/security/security_advisories/index.rst
+++ b/docs/security/security_advisories/index.rst
@@ -5,7 +5,9 @@
     :maxdepth: 1
     :glob:
 
-    *
+    stack_seal_vulnerability
+    svc_caller_sp_fetching_vulnerability
+    crypto_multi_part_ops_abort_fail
 
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