add offers count, & minor fixes code standards

app/Datatables/Shop/OrdersDataTable.php

@@ -10,16 +10,16 @@ class OrdersDataTable extends DataTable
 {
     public $model_name = 'orders';
 
-    public function query(Product $model)
+    public function query(Order $model)
     {
-        return self::buildQuery($model);
+        return $this->buildQuery($model);
     }
 
     protected function getColumns()
     {
         return [
             Column::make('name'),
-            self::makeColumnButtons(),
+            $this->makeColumnButtons(),
         ];
     }
 }