Fix broken link to "labelable element" (#559)

* Fix broken link to "labelable element"

Co-authored-by: Scott O'Hara <[email protected]>

Author: patrickhlauke

index.html

@@ -2252,7 +2252,7 @@ <h2 id="docconformance">
             <td>
               <p>
                 If a `label` element is implicitly or explicitly associated with a 
-                <a href="data-html/https://html.spec.whatwg.org/multipage/forms.html#category-label">labelable element</a> then
+                <a data-cite="html/forms.html#category-label">labelable element</a> then
                 <a><strong class="nosupport">no `role`</strong></a>
               </p>
               <p>