point to list attribute mapping

add link to list attribute mapping to help mitigate confusion like: w3c/html-aria#476

Author: scottaohara

index.html

@@ -1994,7 +1994,9 @@ <h3>HTML Element Role Mappings</h3>
               <td class="atk"><div class="general">Use WAI-ARIA mapping</div></td>
               <td class="ax"><div class="general">Use WAI-ARIA mapping</div></td>
               <!-- <td class="naming"></td> -->
-              <td class="comments"></td>
+              <td class="comments">
+                See also <a href="#att-list">`list` attribute mappings</a>.
+              </td>
             </tr>
             <tr tabindex="-1" id="el-input-time">
               <th>