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

chrome/common/extensions/api/content_settings.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": "contentSettings",
     "compiler_options": {
       "generate_type_functions": true
     },
@@ skipping 24 matching lines @@
             "description": "Clear all content setting rules set by this extension.",
             "parameters": [
               {
                 "name": "details",
                 "type": "object",
                 "properties": {
                   "scope": {
                     "type": "string",
                     "enum": ["regular", "incognito_session_only"],
                     "optional": true,
-                    "description": "Where to set the setting (default: regular). One of<br><var>regular</var>: setting for regular profile (which is inherited by the incognito profile if not overridden elsewhere),<br><var>incognito_session_only</var>: setting for incognito profile that can only be set during an incognito session and is deleted when the incognito session ends (overrides regular settings)."
+                    "description": "Where to clear the setting (default: regular). One of<br><var>regular</var>: setting for regular profile (which is inherited by the incognito profile if not overridden elsewhere),<br><var>incognito_session_only</var>: setting for incognito profile that can only be set during an incognito session and is deleted when the incognito session ends (overrides regular settings)."
                   }
                 }
               },
               {
                 "type": "function",
                 "name": "callback",
                 "optional": true,
                 "parameters": []
               }
             ]
@@ skipping 70 matching lines @@
                     "description": "The resource identifier for the content type."
                   },
                   "setting": {
                     "type": "any",
                     "description": "The setting applied by this rule. See the description of the individual ContentSetting objects for the possible values."
                   },
                   "scope": {
                     "type": "string",
                     "enum": ["regular", "incognito_session_only"],
                     "optional": true,
-                    "description": "Where to clear the setting (default: regular). One of<br><var>regular</var>: setting for regular profile (which is inherited by the incognito profile if not overridden elsewhere),<br><var>incognito_session_only</var>: setting for incognito profile that can only be set during an incognito session and is deleted when the incognito session ends (overrides regular settings)."
+                    "description": "Where to set the setting (default: regular). One of<br><var>regular</var>: setting for regular profile (which is inherited by the incognito profile if not overridden elsewhere),<br><var>incognito_session_only</var>: setting for incognito profile that can only be set during an incognito session and is deleted when the incognito session ends (overrides regular settings)."
                   }
                 }
               },
               {
                 "type": "function",
                 "name": "callback",
                 "optional": true,
                 "parameters": []
               }
             ]
@@ skipping 68 matching lines @@
         "$ref": "ContentSetting",
         "description": "Whether to allow sites to show desktop notifications. One of<br><var>allow</var>: Allow sites to show desktop notifications,<br><var>block</var>: Don't allow sites to show desktop notifications,<br><var>ask</var>: Ask when a site wants to show desktop notifications. <br>Default is <var>ask</var>.<br>The primary URL is the main-frame URL. The secondary URL is not used.",
         "value": [
           "notifications",
           {"type":"string", "enum": ["allow", "block", "ask"]}
         ]
       }
     }
   }
 ]