Fix broken link

      requests and for the reverse proxy to load balance and failover among

      them. This group is sometimes called a <em>cluster</em> but Apache httpd's

      term is a <em>balancer</em>. One defines a balancer by leveraging the

      <directive module="mod_proxy">Proxy</directive> and

      <directive module="mod_proxy" type="section">Proxy</directive> and

      <directive module="mod_proxy">BalancerMember</directive> directives as

      shown:

    </p>

    <note type="warning"><title>Warning</title>

      <p>Do not enable the <em>balancer-manager</em> until you have <a

      href="mod_proxy.html#access">secured your server</a>. In

      href="../mod/mod_proxy.html#access">secured your server</a>. In

      particular, ensure that access to the URL is tightly

      restricted.</p>

    </note>