added Floating label to docs and fixed template in field

docs/guide-de/migrating-yii2-bootstrap.md

@@ -16,6 +16,9 @@ Die grössten Änderungen finden Sie hier zusammengefasst:
 
 ### ActiveForm
 
+Es gibt eine neue Konstante [[yii\bootstrap5\ActiveForm::LAYOUT_FLOATING]]. Sie repräsentiert ein neues
+[neues Formular-Layout](https://getbootstrap.com/docs/5.0/forms/floating-labels/) in Bootstrap 5.
+
 ### Breadcrumbs
 
 ### ButtonDropdown

docs/guide-ja/migrating-yii2-bootstrap.md

@@ -16,6 +16,8 @@ yii2-bootstrap5 は、Bootstrap 4 から Bootstrap 5 への移行ガイドに従
 
 ### ActiveForm
 
+新しい定数[[yii\bootstrap5\ActiveForm::LAYOUT_FLOATING]]があります。 Bootstrap5で導入された[新しいフォームレイアウト](https://getbootstrap.com/docs/5.0/forms/floating-labels/)です。
+
 ### Breadcrumbs
 
 ### ButtonDropdown

docs/guide/migrating-yii2-bootstrap.md

@@ -16,6 +16,9 @@ The most notable changes are summarized below:
 
 ### ActiveForm
 
+There is a new constant [[yii\bootstrap5\ActiveForm::LAYOUT_FLOATING]]. It's a 
+[new form layout](https://getbootstrap.com/docs/5.0/forms/floating-labels/) introduced in Bootstrap 5.
+
 ### Breadcrumbs
 
 ### ButtonDropdown

src/ActiveField.php

@@ -518,6 +518,9 @@ class ActiveField extends \yii\widgets\ActiveField
             $config['enableError'] = false;
 
             Html::addCssClass($config['labelOptions'], ['screenreader' => 'visually-hidden']);
+        } elseif ($layout === ActiveForm::LAYOUT_FLOATING) {
+            $config['template'] = "{input}\n{label}\n{error}\n{hint}";
+            Html::addCssClass($config['options'], ['layout' => 'form-floating mt-3']);
         }
 
         return $config;