Docs: Adding page for visual voicemail configuration

Bug: 23352348
Change-Id: I2d92ddf3ce9aae670619fa43750f8351a6045443
diff --git a/src/devices/devices_toc.cs b/src/devices/devices_toc.cs
index 9184b0b..e5ef0ad 100644
--- a/src/devices/devices_toc.cs
+++ b/src/devices/devices_toc.cs
@@ -199,6 +199,7 @@
           <li><a href="<?cs var:toroot ?>devices/tech/config/renderer.html">OpenGLRenderer</a></li>
           <li><a href="<?cs var:toroot ?>devices/tech/config/runtime_perms.html">Runtime Permissions</a></li>
           <li><a href="<?cs var:toroot ?>devices/tech/config/uicc.html">UICC</a></li>
+          <li><a href="<?cs var:toroot ?>devices/tech/config/voicemail.html">Visual Voicemail</a></li>
         </ul>
       </li>