mod_proxy_fcgi.xml: add more context to the conn reuse note

    By default mod_proxy (configured with <code>enablereuse=on</code>)

    allows a connection pool of

    <directive module="mpm_common">ThreadsPerChild</directive> connections to the

    backend for each httpd process, so the following use cases should be taken

    into account:</p>

    backend for each httpd process when using a threaded mpm (like

    <module>worker</module> or <module>event</module>),

    so the following use cases should be taken into account:</p>

    <ul>

      <li>Under HTTP/1.1 load it will likely cause the creation of up to

      <directive module="mpm_common">MaxRequestWorkers</directive>