Added searchbox to documentation.

This provides the entry point of the documentation search feature.

Change-Id: Iea2b707995c0e042829db509927384dcec7aaf43
diff --git a/Documentation/config-auto-site-initialization.txt b/Documentation/config-auto-site-initialization.txt
index 4c204fd..6111d5d 100644
--- a/Documentation/config-auto-site-initialization.txt
+++ b/Documentation/config-auto-site-initialization.txt
@@ -80,3 +80,6 @@
 GERRIT
 ------
 Part of link:index.html[Gerrit Code Review]
+
+SEARCHBOX
+---------