Docs: HWC2 updates, new section+subsections
      Removing Framebuffer bullet
      Making OpenGL 3.x drivers optional
      Fixing horrendous typo in nav
      Adding Clay's feedback

Bug: 28419158

Change-Id: I19ce49d22f7bdb54229363580d9075f71037ef9c
diff --git a/src/devices/devices_toc.cs b/src/devices/devices_toc.cs
index 75462ad..86b4315 100644
--- a/src/devices/devices_toc.cs
+++ b/src/devices/devices_toc.cs
@@ -145,7 +145,19 @@
         </div>
         <ul>
           <li><a href="<?cs var:toroot ?>devices/graphics/architecture.html">Architecture</a></li>
-          <li><a href="<?cs var:toroot ?>devices/graphics/implement.html">Implementation</a></li>
+          <li class="nav-section">
+            <div class="nav-section-header">
+              <a href="<?cs var:toroot ?>devices/graphics/implement.html">
+                <span class="en">Implementing</span>
+              </a>
+            </div>
+            <ul>
+              <li><a href="<?cs var:toroot ?>devices/graphics/implement-hwc.html">Hardware Composer HAL</a></li>
+              <li><a href="<?cs var:toroot ?>devices/graphics/implement-vsync.html">VSYNC</a></li>
+              <li><a href="<?cs var:toroot ?>devices/graphics/implement-vulkan.html">Vulkan</a></li>
+              <li><a href="<?cs var:toroot ?>devices/graphics/implement-vdisplays.html">Virtual Displays</a></li>
+            </ul>
+         </li>
          <li class="nav-section">
             <div class="nav-section-header">
               <a href="<?cs var:toroot ?>devices/graphics/testing.html">