refine: make billing section more discoverable

Author: ankur-arch

apps/docs/content/docs/guides/postgres/vercel.mdx

@@ -61,6 +61,12 @@ In the local version of your project where you have your `DATABASE_URL` set, run
 npx prisma studio
 ```
 
+## Billing and pricing
+
+Prisma Postgres uses [usage-based pricing](https://www.prisma.io/pricing) based on operations and storage. The same plans and rates apply when you create a database via the Vercel Marketplace, and your Prisma Postgres usage is billed through your Vercel account.
+
+To change your plan, see [How do I upgrade my plan if I am using Prisma Postgres via Vercel?](/postgres/faq#how-do-i-upgrade-my-plan-if-i-am-using-prisma-postgres-via-vercel) in the Prisma Postgres FAQ.
+
 ## Additional considerations when using with Prisma ORM
 
 ### Ensure your project uses the correct environment variable

apps/docs/content/docs/postgres/faq.mdx

@@ -238,7 +238,7 @@ Every request, whether it hits the database or is served from cache, counts as a
 
 ### How do I upgrade my plan if I am using Prisma Postgres via Vercel?
 
-To upgrade your plan via Vercel, follow these steps:
+If you installed Prisma Postgres through the [Vercel Marketplace integration](/guides/postgres/vercel), the same [Prisma Postgres pricing plans](https://www.prisma.io/pricing) apply and your usage is billed through your Vercel account. To upgrade your plan via Vercel, follow these steps:
 
 - Open your [Vercel](https://vercel.com/) Dashboard.
 - Go to the **Integrations** tab in your Vercel Team.