Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/history.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": "history",
+    "description": "Use the <code>chrome.history</code> module to intereact with the browser's record of visited pages. You can add, remove, and query for URLs in the browser's history.",
     "types": [
       {
         "id": "HistoryItem",
         "type": "object",
         "description": "An object encapsulating one result of a history query.",
         "properties": {
           "id": {"type": "string", "minimum": 0, "description": "The unique identifier for the item."},
           "url": {"type": "string", "optional": true, "description": "The URL navigated to by a user."},
           "title": {"type": "string", "optional": true, "description": "The title of the page when it was last loaded."},
           "lastVisitTime": {"type": "number", "optional": true, "description": "When this page was last loaded, represented in milliseconds since the epoch."},
@@ skipping 153 matching lines @@
             "properties": {
               "allHistory": { "type": "boolean", "description": "True if all history was removed.  If true, then urls will be empty." },
               "urls": { "type": "array", "items": { "type": "string" }, "optional": true}
             }
           }
         ]
       }
     ]
   }
 ]