Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/web_request.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": "webRequest",
+    "description": "Use the <code>chrome.webRequest</code> module to intercept, block, or modify requests in-flight and to observe and analyze traffic.",
     "properties": {
       "MAX_HANDLER_BEHAVIOR_CHANGED_CALLS_PER_10_MINUTES": {
         "value": 20,
         "description": "The maximum number of times that <code>handlerBehaviorChanged</code> can be called per 10 minute sustained interval. <code>handlerBehaviorChanged</code> is an expensive function call that shouldn't be called often."
       }
     },
     "types": [
       {
         "id": "RequestFilter",
         "type": "object",
@@ skipping 515 matching lines @@
           {
             "$ref": "RequestFilter",
             "name": "filter",
             "description": "A set of filters that restricts the events that will be sent to this listener."
           }
         ]
       }
     ]
   }
 ]