Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/file_system.idl

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // 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,
     // a description will be automatically generated; typically containing an
     // expanded list of valid extensions (e.g. "text/html" may expand to
     // "*.html, *.htm").
     DOMString? description;
 
     // Mime-types to accept, e.g. "image/jpeg" or "audio/*". One of mimeTypes or
     // extensions must contain at least one valid element.
@@ skipping 59 matching lines @@
     [nocompile] static FileEntry getEntryById(DOMString id);
 
     // Returns the id of the given file entry. This can be used to retrieve file
     // entries with getEntryById(). When an app is restarted (ie: it is sent the
     // onRestarted event) it can regain access to the file entries it had by
     // remembering their ids and calling getEntryById().
     [nocompile] static DOMString getEntryId(
         [instanceOf=FileEntry] object fileEntry);
   };
 };