docs: fix broken bun.sh Nextjs documentation link (#92698)
### What?
Update outdated bun.sh Next.js documentation link.
### Why?
The previous link returned a 404.
### How?
Replaced:
https://bun.sh/docs/frameworks/nextjs
With:
https://bun.com/docs/guides/ecosystem/nextjs
Co-authored-by: Joseph <joseph.chamochumbi@vercel.com>
