docs: M Preview - update the preview section TOC

Change-Id: I5776d367df3baec13aee27a8e920de9d9b69782d

docs/html/preview/preview_toc.cs

@@ -5,14 +5,36 @@
       Program Overview</a></div>
   </li>
 
+  <li class="nav-section">
+    <div class="nav-section-header empty"><a href="<?cs var:toroot ?>preview/download.html">
+      Download</a></div>
+  </li>
+
   <li class="nav-section">
     <div class="nav-section-header empty"><a href="<?cs var:toroot ?>preview/setup-sdk.html">
       Set up the SDK</a></div>
   </li>
 
   <li class="nav-section">
-    <div class="nav-section-header empty"><a href="<?cs var:toroot ?>preview/api-overview.html">
+    <div class="nav-section-header"><a href="<?cs var:toroot ?>preview/testing/guide.html">
+      Testing Guide</a></div>
+      <ul>
+        <li><a href="<?cs var:toroot ?>preview/testing/performance.html">
+          Performance Testing</a></li>
+      </ul>
+  </li>
+
+  <li class="nav-section">
+    <div class="nav-section-header"><a href="<?cs var:toroot ?>preview/api-overview.html">
       API Overview</a></div>
+      <ul>
+        <li><a href="<?cs var:toroot ?>preview/features/runtime-permissions.html">
+          Runtime Permissions</a></li>
+        <li><a href="<?cs var:toroot ?>preview/features/app-linking.html">
+          App Linking</a></li>
+        <li><a href="<?cs var:toroot ?>preview/backup/index.html">
+          Automatic Backups</a></li>
+      </ul>
   </li>
 
   <li class="nav-section">
@@ -20,34 +42,11 @@
       Behavior Changes</a></div>
   </li>
 
-  <li class="nav-section">
-    <div class="nav-section-header empty">
-    <a href="<?cs var:toroot ?>preview/features/runtime-permissions.html">
-      Runtime Permissions</a></div>
-  </li>
-
-  <li class="nav-section">
-    <div class="nav-section-header empty">
-    <a href="<?cs var:toroot ?>preview/backup/index.html">
-      Automatic Backups</a></div>
-  </li>
-
-  <li class="nav-section">
-    <div class="nav-section-header empty">
-    <a href="<?cs var:toroot ?>preview/data-binding/guide.html">
-      Data Binding</a></div>
-  </li>
-
   <li class="nav-section">
     <div class="nav-section-header empty"><a href="<?cs var:toroot ?>preview/samples.html">
       Samples</a></div>
   </li>
 
-  <li class="nav-section">
-    <div class="nav-section-header empty"><a href="<?cs var:toroot ?>preview/reference.html">
-      Reference</a></div>
-  </li>
-
   <li class="nav-section">
     <div class="nav-section-header empty"><a href="<?cs var:toroot ?>preview/support.html">
       Support</a></div>