Link to list of system properties.

Submitted by:	Ernst de Haan <ernst@jollem.com>


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@269042 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/using.html

@@ -201,6 +201,8 @@ This is resolved as <code>build/classes</code>.</p>
 defined using a <code>&lt;property&gt;</code> task.
 For example, <code>${os.name}</code> expands to the
 name of the operating system.</p>
+<p>For a list of system properties see 
+<a href="http://java.sun.com/j2se/1.3/docs/api/java/lang/System.html#getProperties()">the Javadoc of System.getProperties</a>.
 <p>In addition, Ant has some built-in properties:</p>
 <pre>
 basedir             the absolute path of the project's basedir (as set