6977887: (doc) Java 6 API missing info about encoding parameter in storeToXML method

Reviewed-by: sherman

jdk/src/share/classes/java/util/Properties.java

@@ -912,9 +912,13 @@ class Properties extends Hashtable<Object,Object> {
      *
      * <p>The specified stream remains open after this method returns.
      *
-     * @param os the output stream on which to emit the XML document.
-     * @param comment a description of the property list, or <code>null</code>
-     *        if no comment is desired.
+     * @param os        the output stream on which to emit the XML document.
+     * @param comment   a description of the property list, or <code>null</code>
+     *                  if no comment is desired.
+     * @param  encoding the name of a supported
+     *                  <a href="../lang/package-summary.html#charenc">
+     *                  character encoding</a>
+     *
      * @throws IOException if writing to the specified output stream
      *         results in an <tt>IOException</tt>.
      * @throws NullPointerException if <code>os</code> is <code>null</code>,