Issue with the "Fly Postgres" doc - re: postgres forking suggestion

[Black-Milk]

I found an issue with this document.

Title: Fly Postgres
Location: /docs/postgres/
Source: https://github.com/superfly/docs/blob/main/postgres/index.html.md

Describe the issue

The article should probably be changed so that the user is directed to fork from fly-apps/postgres-flex instead.