update doc of propertyset to reflect the code

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@278029 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/CoreTypes/propertyset.html

@@ -60,7 +60,7 @@ set.</p>
       given string.</td>
   </tr>
   <tr>
-    <td valign="top">regexp</td>
+    <td valign="top">regex</td>
     <td valign="top">Select the properties that match the given
       regular expression.  Similar to <a
       href="mapper.html#regexp-mapper">regexp type mappers</a>, this