Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/cookies.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": "cookies",
+    "description": "The cookies module allows you to work with HTTP cookies.",
     "types": [
       {
         "id": "Cookie",
         "type": "object",
         "description": "Represents information about an HTTP cookie.",
         "properties": {
           "name": {"type": "string", "description": "The name of the cookie."},
           "value": {"type": "string", "description": "The value of the cookie."},
           "domain": {"type": "string", "description": "The domain of the cookie (e.g. \"www.google.com\", \"example.com\")."},
           "hostOnly": {"type": "boolean", "description": "True if the cookie is a host-only cookie (i.e. a request's host must exactly match the domain of the cookie)."},
@@ skipping 172 matching lines @@
               "removed": {"type": "boolean", "description": "True if a cookie was removed."},
               "cookie": {"$ref": "Cookie", "description": "Information about the cookie that was set or removed."},
               "cause": {"min_version": "12.0.707.0", "type": "string", "enum": ["evicted", "expired", "explicit", "expired_overwrite", "overwrite"], "description": "The underlying reason behind the cookie's change. If a cookie was inserted, or removed via an explicit call to \"chrome.cookies.remove\", \"cause\" will be \"explicit\". If a cookie was automatically removed due to expiry, \"cause\" will be \"expired\". If a cookie was removed due to being overwritten with an already-expired expiration date, \"cause\" will be set to \"expired_overwrite\".  If a cookie was automatically removed due to garbage collection, \"cause\" will be \"evicted\".  If a cookie was automatically removed due to a \"set\" call that overwrote it, \"cause\" will be \"overwrite\". Plan your response accordingly."}
             }
           }
         ]
       }
     ]
   }
 ]