delete.html: add example of deleting a directory

Obtained from: Ivan Ivanov


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@276597 13f79535-47bb-0310-9956-ffa450edef68

CONTRIBUTORS

@@ -70,6 +70,7 @@ Holger Engels
 Ingenonsya France
 Ingmar Stein
 Irene Rusman
+Ivan Ivanov
 Jack J. Woehr
 James Duncan Davidson
 Jan Matèrne

docs/manual/CoreTasks/delete.html

@@ -159,6 +159,12 @@ and any subdirectories.</p>
 </pre>
 <p>deletes all files and subdirectories of <code>build</code>, including
 <code>build</code> itself.</p>
+<pre>  &lt;delete includeemptydirs=&quot;true&quot;&gt;
+    &lt;fileset dir=&quot;build&quot; includes=&quot;**/*&quot;/&gt;
+  &lt;/delete&gt;
+</pre>
+<p>deletes all files and subdirectories of <code>build</code>, without
+<code>build</code> itself.</p>
 <hr><p align="center">Copyright &copy; 2000-2002,2004 The Apache Software Foundation.
 All rights Reserved.</p>