Add example of role=“doc-subtitle”

Author: ericwbailey

partials/section.headings.hbs

@@ -36,9 +36,14 @@
     <h2>Title</h2>
     <p>Subtitle</p>
   </header>
+  <header>
+    <h2>Title</h2>
+    <p role="doc-subtitle">Subtitle</p>
+  </header>
 
   <h2 id="notes-headings">Notes:</h2>
-  <p>
-    <small>Ensure that headings create a logical order. Apply <abbr="Cascading Style Sheets">CSS</abbr> classes to control visual presentation (e.g. <code translate="no">&lt;h2 class=&quot;type-size-medium color-blue-dark&quot;&gt;Our services&lt;/h2&gt;</code> ).</small>
-  </p>
+  <ul>
+    <li><small>Ensure that headings create a logical order. Apply <abbr="Cascading Style Sheets">CSS</abbr> classes to control visual presentation (e.g. <code translate="no">&lt;h2 class=&quot;type-size-medium color-blue-dark&quot;&gt;Our services&lt;/h2&gt;</code> ).</small></li>
+    <li><small><code translate="no">role="doc-subtitle"</code> is used to alternate title for the work, but still has limited support.</small></li>
+  </ul>
 </section><!-- End of #section-headings -->