Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/storage.json

 // 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.
 
 [
   {
     "namespace": "storage",
+    "description": "Use the <code>chrome.storage</code> module to store, retrieve, and track changes to user data.",
     "unprivileged": true,
     "types": [
       {
         "id": "StorageChange",
         "type": "object",
         "properties": {
           "oldValue": {
             "type": "any",
             "description": "The old value of the item, if there was an old value.",
             "optional": true
@@ skipping 192 matching lines @@
       },
       "managed": {
         "$ref": "StorageArea",
         "description": "Items in the <code>managed</code> storage area are set by the domain administrator, and are read-only by the extension; trying to modify this namespace results in an error.",
         "value": [ "managed" ],
         "nodoc": true
       }
     }
   }
 ]