Add html builder postAjax docs.

Author: jaydons

html-builder-post-ajax.md

@@ -0,0 +1,35 @@
+# Html Builder Post Ajax
+
+Use post method to submit the dataTables ajax request.
+
+See [datatables.net](https://datatables.net/) official documentation for [`ajax option`](https://datatables.net/reference/option/ajax) for details.
+
+**Syntax**
+```php
+$builder->postAjax($attributes);
+```
+
+## Post Ajax Parameter
+Ajax parameter (`$attributes`) can either be a string or an array.
+
+**String Attributes**
+
+When the attribute passed is a `string`. The builder will treat this as the `URL` where we fetch our data.
+
+```php
+$builder->postAjax(route('users.data'));
+```
+
+> {tip} Setting ajax to `null` or `empty string` will use the current url where DataTables was used.
+
+**Array Attributes**
+
+Attributes are the same with the `ajax()` method request valid parameters.
+
+```php
+$builder->postAjax([
+    'url' => route('users.data'),
+])
+```
+
+