Provide clarification for <div>'s implicit role (mdn#4893)

files/en-us/web/html/element/div/index.html

@@ -71,6 +71,10 @@ <h2 id="Usage_notes">Usage notes</h2>
  <li>The <code>&lt;div&gt;</code> element should be used only when no other semantic element (such as {{HTMLElement("article")}} or {{HTMLElement("nav")}}) is appropriate.</li>
 </ul>
 
+<h2 id="Accessibility_concerns">Accessibility concerns</h2>
+
+The <code>&lt;div&gt;</code> element has <a href="https://www.w3.org/TR/wai-aria-1.2/#generic">an implicit role of <code>generic</code></a>, and not none. This may affect certain ARIA combination declarations that expect a direct descendant element with a certain role to function properly.
+
 <h2 id="Examples">Examples</h2>
 
 <h3 id="A_simple_example">A simple example</h3>