Update copyfile documentation

Submitted by:	uli stehling <uli.stehling@informationsdesign.de>


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@267935 13f79535-47bb-0310-9956-ffa450edef68

docs/index.html

@@ -1183,6 +1183,12 @@ does not exist.</p>
       the copy</td>
     <td valign="top" align="center">No</td>
   </tr>
+  <tr>
+    <td valign="top">forceoverwrite</td>
+    <td valign="top">overwrite existing files even if the destination
+      files are newer (default is false).</td>
+    <td valign="top" align="center">No</td>
+  </tr>
 </table>
 <h3>Examples</h3>
 <blockquote>