Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/file_system.idl

Index: chrome/common/extensions/api/file_system.idl
diff --git a/chrome/common/extensions/api/file_system.idl b/chrome/common/extensions/api/file_system.idl
index def73bffc5bcd540488529f1c3a3b499c5b35d58..6812e2c2f48d14314f0d6bb72b068de46b368e3a 100644
--- a/chrome/common/extensions/api/file_system.idl
+++ b/chrome/common/extensions/api/file_system.idl
@@ -2,6 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Use the <code>chrome.fileSystem</code> module to create, read, navigate,
+// and write to a sandboxed section of the user's local file system. With this
+// API, packaged apps can read and write to a user-seleced location. For
+// example, a text editor app can use the API to read and write local documents.
+
+[availability=23]
 namespace fileSystem {
   dictionary AcceptOption {
     // This is the optional text description for this option. If not present,