Update: missing type on input reference

re: w3c/html-aria#476

mention in the comments for the input type=text element that if an input has a missing value then it defaults to the text state - as defined by HTML.

index.html

@@ -1957,7 +1957,8 @@ <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">An `input` with a missing <a data-cite="html/input.html#attr-input-type">`type` attribute</a> 
+                defaults to the Text state.</td>
             </tr>
             <tr tabindex="-1" id="el-input-textetc-autocomplete">
               <th>