[css-writing-modes] Be more precise for Computed Value of text-combine-horizontal

Author: fantasai

css-writing-modes/Overview.src.html

@@ -2434,7 +2434,7 @@ <h3 id="text-combine-horizontal">
       </tr>
       <tr>
         <th>Computed&#160;value:</th>
-        <td>specified value</td>
+        <td>specified keyword, plus integer if ''digits''</td>
       </tr>
     </tbody>
   </table>