A back quote sign in docblock missed.

introduced in https://github.com/yiisoft/yii2/commit/bf206efc66bc47b693271359e433679c1618189b

Fixes #6427: In case of invalid route web application now throws exception with "Page not found" instead of "Invalid Route"

Fixes #6434: Added `yii\behaviors\SluggableBehavior::immutable` to support keeping the generated slug unchanged

Fixes #6467: `ActiveForm` will scroll to the nearest visible element when the first error input is hidden

better readability

eg. used in /var/www/app/vendor/yiisoft/yii2/base/Security.php at line 465

Signed-off-by: nabi <nabikaz@gmail.com>

Fixes #6404: advanced application template `Alert` widget was generating duplicate IDs in case of multiple flashes

Fixes #5494: Added support for specifying a menu header as a configuration array in `yii\bootstrap\Dropdown`

Fixes #6345

Fixes #6367: Added `yii\gii\generators\crud\Generator` to support customizing view path for the generated CRUD controller

Fixes #4395: Added `$checkAjax` parameter to `yii\web\Response::redirect()` to support default redirection behavior for AJAX/PJAX requests

Fixes #5070: Gii controller generator should use controller class name instead of controller ID to specify new controller

fixes #5503