Added tree status (#12)

Added tree status

README.md

@@ -12,6 +12,7 @@ GitHub | `app_manifest_token` | This cookie is used during the App Manifest flow
 GitHub | `color_mode` | This cookie is used to indicate the user selected theme preference. | Session
 GitHub | `_device_id` | This cookie is used to track recognized devices for security purposes. | One year
 GitHub | `dotcom_user` | This cookie is used to signal to us that the user is already logged in. | One year
+GitHub | `fileTreeExpanded` | Used to indicate whether the file tree on the code view was last expanded or collapsed | 30 days
 GitHub | `ghcc` | This cookie validates user's choice about cookies | 180 Days
 GitHub | `_gh_ent` | This cookie is used for temporary application and framework state between pages like what step the customer is on in a multiple step form. | Two weeks
 GitHub | `_gh_sess` | This cookie is used for temporary application and framework state between pages like what step the user is on in a multiple step form. | Session