Another -Xbootstrap typo.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@832939 13f79535-47bb-0310-9956-ffa450edef68

docs/manual/using.html

@@ -491,7 +491,7 @@ can be written as:
     <fileset dir="lib" includes="*.jar"/>
   </path>
   <javac srcdir="src" destdir="classes">
-    <compilerarg arg="-Xbootstrap/p:${toString:lib.path.ref}"/>
+    <compilerarg arg="-Xbootclasspath/p:${toString:lib.path.ref}"/>
   </javac>
 </pre>