Update dcat/index.html

Co-Authored-By: Riccardo Albertoni <albertoni@ge.imati.cnr.it>

dcat/index.html

@@ -163,7 +163,7 @@ <h3>Namespaces appearing in recommendations</h3>
 
         </section>
         <section class="informative">
-          <h3>Namespaces appearing in examples</h3>
+          <h3>Non-normative namespaces</h3>
           <p>Namespaces and prefixes used in examples and guidelines  in the document and not from normative parts of the recommendation are shown in the following table.</p>
 
           <table id="table-namespaces-examples">