[ref/using_frama-c] from upper to lower case

html/using-frama-c.html

@@ -107,7 +107,7 @@ css: plugin
 
                 <div id="group_security_defects">
                   <div class="paragraphGroup">
-                    <h3>Detect Security Defects</h3>
+                    <h3>Detect security defects</h3>
 
                     <p>Frama-C allows to verify that the source code complies with a provided formal specification. Functional
                     specifications can be written in a dedicated language, ACSL. The specifications can be partial, concentrating