Fix some typos, broken links and other issues in extension docs

chrome/common/extensions/api/page_action.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": "pageAction",
     "dependencies": [ "tabs" ],
     "types": [
       {
@@ skipping 32 matching lines @@
             "properties": {
               "tabId": {"type": "integer", "minimum": 0, "description": "The id of the tab for which you want to modify the page action."},
               "title": {"type": "string", "description": "The tooltip string."}
             }
           }
         ]
       },
       {
         "name": "getTitle",
         "type": "function",
-        "description": "Gets the title of the browser action.",
+        "description": "Gets the title of the page action.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "properties": {
               "tabId": {
                 "type": "integer",
                 "description": "Specify the tab to get the title from."
               }
             }
@@ skipping 78 matching lines @@
                 "type": "string",
                 "description": "The html file to show in a popup.  If set to the empty string (''), no popup is shown."
               }
             }
           }
         ]
       },
       {
         "name": "getPopup",
         "type": "function",
-        "description": "Gets the html document set as the popup for this browser action.",
+        "description": "Gets the html document set as the popup for this page action.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "properties": {
               "tabId": {
                 "type": "integer",
                 "description": "Specify the tab to get the popup from."
               }
             }
@@ skipping 19 matching lines @@
         "parameters": [
           {
             "name": "tab",
             "$ref": "tabs.Tab"
           }
         ]
       }
     ]
   }
 ]