Elim detached_panel type and update chrome.windows documentation

chrome/common/extensions/docs/templates/json/whats_new.json

 {
     "backgroundpages.to-be-non-persistent": {
         "type": "additionsToExistingApis",
         "description": "Background pages can optionally be non-persistent, using a feature we call <code>event pages</code>. Event pages run only while they're being used, and will unload when idle to save resources.",
         "version": 22
     },
     "chromeSetting.set-regular-only-scope": {
         "type": "additionsToExistingApis",
         "description": "The types.ChromeSetting.set method now has a <code>regular_only</code> scope.",
         "version": 21
@@ skipping 153 matching lines @@
         "description": "You are no longer required to specify the <code>tabId</code> for the tabs.update method. When not provided, the tabId defaults to the selected tab of the current window.",
         "version": 16
     },
     "external-files-be-owned-by-users-in-wheel-group": {
         "type": "additionsToExistingApis",
         "description": "External extension files on Mac OS can now be owned by users within a wheel group (or an admin group).",
         "version": 16
     },
     "experimental-permission-no-longer-required-for-panel-type": {
         "type": "additionsToExistingApis",
-        "description": "The experimental permission is no longer required for the panel type. By default, the panel type creates a popup unless the <code>--enable-panels</code> flag is set.",
+        "description": "Experimental permission for deprecated windows.create panel type.",
         "version": 16
     },
     "offline_enabled.field-specify-without-connection": {
         "type": "manifestChanges",
         "description": "The new offline_enabled field lets you specify that your app works well even without an internet connection.",
         "version": 15
     },
     "management.getPermissionWarningsById.retrieve-permission-warning": {
         "type": "additionsToExistingApis",
         "description": "You can retrieve permission warnings using the new management API methods management.getPermissionWarningsById and management.getPermissionWarningsByManifest.",
@@ skipping 173 matching lines @@
         "type": "additionsToExistingApis",
         "description": "A new windows.WINDOW_ID_NONE constant identifies when focus shifts away from the browser.",
         "version": 6
     },
     "tabs.getCurrent-returns-tab": {
         "type": "additionsToExistingApis",
         "description": "The new tabs.getCurrent method returns the tab associated with the currently executing script.",
         "version": 6
     }
 }