Manual <mail>: small fix layout

manual/Tasks/mail.html

@@ -162,7 +162,7 @@
     <td valign="top">ssl</td>
     <td valign="top">"true", "on" or "yes" accepted here<br></br>
     indicates whether you need TLS/SSL</td>
-    <td valign="center">No</td>
+    <td align="center" valign="top">No</td>
   </tr>
   <tr>
     <td valign="top">encoding</td>
@@ -197,7 +197,7 @@
       whether the STARTTLS command used to switch to an encrypted
       connection for authentication should be supported.  Requires
       JavaMail.  <em>Since Ant 1.8.0</em></td>
-    <td valign="center">No</td>
+    <td align="center" valign="top">No</td>
   </tr>
 </table>