improve the result of pr 2570

We improve the language in `SECURITY.md` and the resulting
`SECURITY.html` page, and add an important disclaimer.  We also add
that same disclaimer to the bottom of the of the main `index.html`
we page (via `index.md`).

bin/md2html.cfg

@@ -227,23 +227,6 @@ index.md
 	-D
 	./
 
-SECURITY.md
-	-H
-	navbar=empty
-	-o
-	bin/subst.default.sh
-	-s
-	TITLE=The International Obfuscated C Code Contest
-	-s
-	DESCRIPTION=International Obfuscated C Code Contest - Security Policy
-	-s
-	KEYWORDS=Security
-	-H
-	header=no-header-2
-	-D
-	./
-
-
 judges.md
 	-H
 	navbar=empty
@@ -390,6 +373,22 @@ nojs-menu.md
 	-D
 	./
 
+SECURITY.md
+	-H
+	navbar=empty
+	-o
+	bin/subst.default.sh
+	-s
+	TITLE=The International Obfuscated C Code Contest
+	-s
+	DESCRIPTION=International security policy
+	-s
+	KEYWORDS=IOCCC, security, security policy
+	-s
+	HEADER_2=IOCCC Security Policy
+	-D
+	./
+
 status.md
 	-H
 	navbar=empty