Update TOC

Author: cheneym2

docs/user-guide/toc.html

@@ -58,6 +58,7 @@
 <li data-link="modules#defining-a-module"><span>Defining a Module</span></li>
 <li data-link="modules#importing-a-module"><span>Importing a Module</span></li>
 <li data-link="modules#access-control"><span>Access Control</span></li>
+<li data-link="modules#organizing-systems-of-modules"><span>Organizing Systems of Modules</span></li>
 <li data-link="modules#legacy-modules"><span>Legacy Modules</span></li>
 </ul>
 </li>
@@ -265,4 +266,4 @@
 </li>
 </ul>
 </li>
-</ul>
+</ul>