Add reference to mod_proxy_ajp and mod_proxy_balancer.

<?xml version="1.0"?>

<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">

<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>

<!-- $Revision: 1.34 $ -->

<!-- $Revision: 1.35 $ -->

<!--

 Copyright 2002-2004 The Apache Software Foundation

    </note>

    <p>This module implements a proxy/gateway for Apache. It implements

    proxying capability for <code>FTP</code>, <code>CONNECT</code> (for SSL),

    proxying capability for <code>AJP13</code> (Apache JServe Protocol

    version 1.3), <code>FTP</code>, <code>CONNECT</code> (for SSL),

    <code>HTTP/0.9</code>, <code>HTTP/1.0</code>, and <code>HTTP/1.1</code>.

    The module can be configured to connect to other proxy modules for these

    and other protocols.</p>

    <p>Apache's proxy features are divided into several modules in

    addition to <module>mod_proxy</module>:

    <module>mod_proxy_http</module>, <module>mod_proxy_ftp</module>

    <module>mod_proxy_http</module>, <module>mod_proxy_ftp</module>,

    <module>mod_proxy_ajp</module>, <module>mod_proxy_balancer</module>,

    and <module>mod_proxy_connect</module>.  Thus, if you want to use

    one or more of the particular proxy functions, load

    <module>mod_proxy</module> <em>and</em> the appropriate module(s)