Add references to Apachetutor in developer docs

      <li><a href="http://www.onlamp.com/pub/ct/38">Some notes on 

      Apache module development by Ryan Bloom</a></li>

      <li>Developer articles at <a href="http://www.apachetutor.org/">apachetutor</a> include:

      <ul>

        <li><a href="http://www.apachetutor.org/dev/request">Request Processing in Apache</a></li>

        <li><a href="http://www.apachetutor.org/dev/config">Configuration for Modules</a></li>

        <li><a href="http://www.apachetutor.org/dev/pools">Resource Management in Apache</a></li>

        <li><a href="http://www.apachetutor.org/dev/reslist">Connection Pooling in Apache</a></li>

        <li><a href="http://www.apachetutor.org/dev/brigades">Introduction to Buckets and Brigades</a></li>

      </ul></li>

    </ul>

</section>

</manualpage>