Dynamically generate a heading for Extension Docs API pages

chrome/common/extensions/api/input_ime.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": "input.ime",
+    "description": "Use the <code>chrome.input.ime</code> module to implement a custom IME for Chrome OS. This allows your extension to handle keystrokes, set the composition, and manage the candidate window.",
     "platforms": ["chromeos"],
     "types": [
       {
         "id": "KeyboardEvent",
         "type": "object",
         "description": "See http://www.w3.org/TR/DOM-Level-3-Events/#events-KeyboardEvent",
         "properties": {
           "type": {"type": "string", "description": "One of keyup or keydown.", "enum": ["keyup", "keydown"]},
           "requestId": {"type": "string", "description": "The ID of the request."},
           "key": {"type": "string", "description": "Value of the key being pressed"},
@@ skipping 600 matching lines @@
                 "type": "integer",
                 "description": "The beginning position of the selection. This value indicates caret position if is no selection."
               }
             }
           }
         ]
       }
     ]
   }
 ]