Doc change: add new engagement and other distribute files.

Change-Id: I1c80d134b6637db9f763b6a587cdc5817a66b9be
diff --git a/docs/html/design/index.jd b/docs/html/design/index.jd
index 638f35b..1ffb0a3 100644
--- a/docs/html/design/index.jd
+++ b/docs/html/design/index.jd
@@ -41,8 +41,12 @@
     </div>
   </div>
 </section>
-
-<section class="dac-section dac-gray dac-small dac-invert"><div class="wrap">
+<div class="wrap dac-offset-parent">
+  <a class="dac-fab dac-scroll-button" data-scroll-button href="#latest">
+    <i class="dac-sprite dac-arrow-down-gray"></i>
+  </a>
+</div>
+<section class="dac-section dac-gray dac-small dac-invert" id="latest"><div class="wrap">
   <h2 class="norule">Latest</h2>
   <div class="resource-widget resource-flow-layout col-16"
        data-query="collection:design/landing/latest"