Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/runtime.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": "runtime",
+    "description": "Use the <code>chrome.runtime</code> module to retrieve the background page, return details about the manifest, and listen for and respond to events in the app or extension lifecycle. You can also use this API to convert the relative path of URLs to fully-qualified URLs.",
+    "documentation_permissions_required": ["runtime"],
     "types": [
       {
         "id": "Port",
         "type": "object",
         "nocompile": true,
         "description": "An object which allows two way communication with other pages.",
         "properties": {
           "name": {"type": "string"},
           "disconnect": { "type": "function" },
           "onDisconnect": { "$ref": "events.Event" },
@@ skipping 408 matching lines @@
           "optional": "true",
           "description": "Return true from the event listener if you wish to call <code>sendResponse</code> after the event listener returns."
         }
       }
 
 
 
     ]
   }
 ]