docs: added code blocks without headers (#2560)

docs/content/advanced/backend/price-lists/use-api.mdx

@@ -37,7 +37,7 @@ When you create a price list, you can specify different conditions to control wh
 
 In the body of your request, aside from the required fields, you can send the following fields to apply different conditions:
 
-```js
+```js noHeader
 {
   prices: [
     {