bmcweb Add DELETE to allowed XSS methods

When in cross site scripting mode, delete should be allowed, along with
PATCH, PUT, and POST, to delete values.

Change-Id: If59594b6a01794c843c0290249bd397b9e305a3e
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/include/security_headers_middleware.hpp b/include/security_headers_middleware.hpp
index 4ef864b..872f4aa 100644
--- a/include/security_headers_middleware.hpp
+++ b/include/security_headers_middleware.hpp
@@ -47,7 +47,8 @@
         res.addHeader(bf::access_control_allow_methods, "GET, "
                                                         "POST, "
                                                         "PUT, "
-                                                        "PATCH");
+                                                        "PATCH, "
+                                                        "DELETE");
         res.addHeader(bf::access_control_allow_credentials, "true");
         res.addHeader(bf::access_control_allow_headers, "Origin, "
                                                         "Content-Type, "