Docs: Audio updates for N + nav changes
      Adding Eric's feedback
      Removing refs to audio_policy.h
      Adding Clay's feedback
      Cleaning up intro statement

Bug: 26686098

Change-Id: Ibe0a61b1a13111b3c45e3c41fcd9fbcaa054fc93
diff --git a/src/devices/devices_toc.cs b/src/devices/devices_toc.cs
index aa1f4a5..4407590 100644
--- a/src/devices/devices_toc.cs
+++ b/src/devices/devices_toc.cs
@@ -80,7 +80,18 @@
       </div>
         <ul>
           <li><a href="<?cs var:toroot ?>devices/audio/terminology.html">Terminology</a></li>
-          <li><a href="<?cs var:toroot ?>devices/audio/implement.html">Implementation</a></li>
+          <li class="nav-section">
+            <div class="nav-section-header">
+              <a href="<?cs var:toroot ?>devices/audio/implement.html">
+                <span class="en">Implementation</span>
+              </a>
+            </div>
+            <ul>
+              <li><a href="<?cs var:toroot ?>devices/audio/implement-policy.html">Policy Configuration</a></li>
+              <li><a href="<?cs var:toroot ?>devices/audio/implement-shared-library.html">Shared Library</a></li>
+              <li><a href="<?cs var:toroot ?>devices/audio/implement-pre-processing.html">Pre-processing Effects</a></li>
+            </ul>
+         </li>
           <li><a href="<?cs var:toroot ?>devices/audio/data_formats.html">Data Formats</a></li>
           <li><a href="<?cs var:toroot ?>devices/audio/attributes.html">Attributes</a></li>
           <li><a href="<?cs var:toroot ?>devices/audio/warmup.html">Warmup</a></li>