Provide a better description of a parameter

manual/Types/filterchain.html

@@ -722,8 +722,8 @@ and <q>//</q></p>
   </tr>
   <tr>
     <td>tablength</td>
-    <td>Defaults to <q>8</q></td>
-    <td>No</td>
+    <td>Amount of space characters to replace a tab character with.</td>
+    <td>No; defaults to <q>8</q></td>
   </tr>
 </table>