Update 400-nextjs-prisma-client-dev-practices.mdx

[zhandosm]

• Add extension to the db file as file=./db was a bit misleading Result: file=./db.ts

Describe this PR

• The explanation for connection bets practices - Best practice for instantiating PrismaClient with Next.js has an exmpale file db with missing extension. This seemed a bit misleading because other parts on the docs have the extension. The screenshots as reference:
• WIth extiension
  
• without extension
  

Changes

• Added extension to the file in the docs

[vercel]

@zhandosm is attempting to deploy a commit to the Prisma Team on Vercel.

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[ruheni]

Thanks for catching and resolving this. 🙏

I've gone ahead and removed the file path prefix, ./ to keep it consistent with the other example.

[ruheni]

Thanks for catching and resolving this. 🙏

I've gone ahead and removed the file path prefix, ./ to keep it consistent with the other example.