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.",
     "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."
               }
             ]
           }
         ]
       }
     ]
   }
 ]