add callback documentation

docs/en/how-to-put-number-format-callback.md

@@ -0,0 +1,22 @@
+# Callback
+
+### Table : Products
+| Field Name | Data Type |
+| ---------- | ----------- |
+| id | int (PK) |
+| name | varchar(255) |
+| price | double |
+
+### Products
+```php
+$this->col[] = ["label"=>"Name","name"=>"name"];
+$this->col[] = ["label"=>"Price","name"=>"price","callback"=>function($row) {
+return number_format($row->price);
+}];
+```
+
+## What's Next
+- [How To Make A Subquery Column in Grid Data](./how-to-make-subquery.md)
+
+## Table Of Contents
+- [Back To Index](./index.md)

docs/en/index.md

@@ -5,7 +5,8 @@
 - **Grid Data Column Section**
   - [How To Add Column In Grid Data](./how-to-add-column.md)
   - [How To Join Table In Grid Data](./how-to-join-in-grid-data.md)
-  - [How To Put Number Format In Grid Data Column](./how-to-put-number-format.md)
+  - [How To Put Number Format In Grid Data Column (callback_php)](./how-to-put-number-format.md)
+  - [How To Put Number Format In Grid Data Column (callback)](./how-to-put-number-format-callback.md)
   - [How To Make A Subquery Column in Grid Data](./how-to-make-subquery.md)
   - [How To Add More Action Button In Grid Data](./how-add-more-action-button.md)
   - [How To Add More Bulk Action In Grid Data](./how-add-bulk-button.md)