Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/permissions.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": "permissions",
+    "description": "Use the <code>chrome.permissions</code> module to implement optional permissions. As of Chrome 16, you can request optional permissions during your extension's regular application flow rather than at install time, so users understand why the permissions are needed and use only those that are necessary.",
     "types": [
       {
         "id": "Permissions",
         "type": "object",
         "properties": {
           "permissions": {
             "type": "array",
             "items": {"type": "string"},
             "optional": true,
             "description": "List of named permissions (does not include hosts or origins)."
@@ skipping 116 matching lines @@
                 "type": "boolean",
                 "description": "True if the permissions were removed."
               }
             ]
           }
         ]
       }
     ]
   }
 ]