Docs: Adding system-level graphics documentation.

Bug: 13787196
Change-Id: I90b4cd725d81ef9dc01b6b5256245b1b082daf40
diff --git a/src/devices/devices_toc.cs b/src/devices/devices_toc.cs
index 3b74d81..9d721e8 100644
--- a/src/devices/devices_toc.cs
+++ b/src/devices/devices_toc.cs
@@ -81,7 +81,16 @@
           <li><a href="<?cs var:toroot ?>devices/tech/storage/config-example.html">Typical Configuration Examples</a></li>
         </ul>
       </li>
-      <li><a href="<?cs var:toroot ?>devices/graphics.html">Graphics</a></li>
+      <li class="nav-section">
+        <div class="nav-section-header">
+          <a href="<?cs var:toroot ?>devices/graphics.html">
+            <span class="en">Graphics</span>
+          </a>
+        </div>
+        <ul>
+          <li><a href="<?cs var:toroot ?>devices/graphics/architecture.html">System-Level Architecture</a></li>
+        </ul>
+      </li>
       <li class="nav-section">
         <div class="nav-section-header">
           <a href="<?cs var:toroot ?>devices/tech/input/index.html">