Docs: Update to home page to announce A/B updates

Test: make online-sac-docs on staging 7
Bug: 34825663
Change-Id: I60ce12ef57e750733251534244d8399b5efd2ce7
diff --git a/src/index.jd b/src/index.jd
index b104013..c07f0b5 100644
--- a/src/index.jd
+++ b/src/index.jd
@@ -44,6 +44,15 @@
   <div class="col-8">
   <h3>What's New</h3>
 
+<h4>Background App Compilation in A/B System Updates</h4>
+
+<p>Examples for
+<strong><a href="{@docRoot}devices/tech/dalvik/configure.html#other_odex">installing</a></strong> and
+<strong><a href="{@docRoot}devices/tech/ota/ab_updates.html#configuration">configuring</a></strong>
+<code>otapreopt_script</code> have been added to explain how to use this tool
+for optimizing user apps so they are ready to run after the device reboots
+during an A/B system update.</p>
+
 <h4>February Android Security Bulletin</h4>
 <p>The <strong><a href="{@docRoot}security/bulletin/2017-02-01.html">February
 2017 Android Security Bulletin</a></strong> has been published along with links
@@ -77,12 +86,6 @@
 href="{@docRoot}security/bulletin/2016-12-01.html">December 2016 Public
 Security Bulletin</a></strong>.</p>
 
-<h4>USB headset specification</h4>
-<p>New guidelines for creating
-<strong><a href="{@docRoot}devices/accessories/headset/usb-headset-spec.html">USB
-headsets</a></strong> have been published, and other headset documentation has
-been updated and reorganized.</p>
-
 <h4>dalvik.annotation.MethodParameters</h4>
 <p>A <code>dalvik.annotation.MethodParameters</code> annotation has been added
 to AOSP after Android 7.1 that is optional and can be used to provide parameter