wrong property name

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@306780 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/CoreTypes/mapper.html

@@ -347,7 +347,7 @@ in a nested <code>&lt;classpath&gt;</code>.</p>
 following algorithm:</p>
 <ul>
 <li>If the system property
-<code>ant.regexp.matcherimpl</code> has been set, it is taken as the
+<code>ant.regexp.regexpimpl</code> has been set, it is taken as the
 name of the class implementing
 <code>org.apache.tools.ant.util.regexp.RegexpMatcher</code> that
 should be used.</li>