added clone button example to readme

Author: Alexander Nesterov

README.md

@@ -109,6 +109,50 @@ use unclead\multipleinput\MultipleInput;
 ```
 See more in [multiple columns](https://github.com/unclead/yii2-multiple-input/wiki/Usage#multiple-columns)
 
+### Clone filled rows
+![Clone button example](https://raw.githubusercontent.com/unclead/yii2-multiple-input/master/resources/images/clone-button.gif)
+```php
+use unclead\multipleinput\MultipleInput;
+
+...
+
+<?= $form->field($model, 'products')->widget(MultipleInput::className(), [
+    'max' => 10,
+    'cloneButton' => true,
+    'columns' => [
+        [
+            'name'  => 'product_id',
+            'type'  => 'dropDownList',
+            'title' => 'Special Products',
+            'defaultValue' => 1,
+            'items' => [
+                1 => 'id: 1, price: $19.99, title: product1',
+                2 => 'id: 2, price: $29.99, title: product2',
+                3 => 'id: 3, price: $39.99, title: product3',
+                4 => 'id: 4, price: $49.99, title: product4',
+                5 => 'id: 5, price: $59.99, title: product5',
+            ],
+        ],
+        [
+            'name'  => 'time',
+            'type'  => DateTimePicker::className(),
+            'title' => 'due date',
+            'defaultValue' => date('d-m-Y h:i')
+        ],
+        [
+            'name'  => 'count',
+            'title' => 'Count',
+            'defaultValue' => 1,
+            'enableError' => true,
+            'options' => [
+                'type' => 'number',
+                'class' => 'input-priority',
+            ]
+        ]
+    ]
+])->label(false);
+```
+
 ## Documentation
 
 You can find a full version of documentation in [wiki](https://github.com/unclead/yii2-multiple-input/wiki/)