Update dcat/index.html

Co-authored-by: Andrea Perego <andrea-perego@users.noreply.github.com>

dcat/index.html

@@ -297,7 +297,7 @@ <h3>DCAT scope</h3>
                  Changes required for the class diagram are tracked in issue <a href="https://github.com/w3c/dxwg/issues/1320">#1320</a>. Switching the format of the diagram to SVG vector graphics is under consideration, see issue <a href="https://github.com/w3c/dxwg/issues/1294">#1294</a>.
               </p>
            </aside>
-    <figure id="UML_DCAT_All_Attr">
+    <figure id="fig-dcat-all-attributes">
       <img alt="UML model of DCAT classes and properties" src="./images/DCAT-summary-all-attributes.svg">
       <figcaption>
           Overview of DCAT model, showing the classes of resources that can be members of a Catalog, and the relationships between them.