docs: redesigned code blocks (#2745)

* docs: redesigned code blocks to include titles

* docs: added a title where necessary

docs/content/advanced/backend/payment/how-to-create-payment-provider.md

@@ -48,7 +48,7 @@ The first step to create a payment provider is to create a JavaScript or TypeScr
 
 For example, create the file `src/services/my-payment.ts` with the following content:
 
-```ts
+```ts title=src/services/my-payment.ts
 import { AbstractPaymentService, Cart, Data, Payment, PaymentSession, PaymentSessionStatus, TransactionBaseService } from "@medusajs/medusa"
 import { EntityManager } from "typeorm";