docs: remove stray backtick from prisma install command

[dewa-nanda]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/docs.nestjs.com/blob/master/CONTRIBUTING.md

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Docs
• Other... Please describe:

What is the current behavior

The documentation contains an incorrect npm install command with a trailing backtick (`), which can cause errors when users copy and paste the command.

Issue Number: N/A

What is the new behavior?

The install command has been corrected by removing the stray backtick, ensuring it can be copied and executed correctly without errors.

Does this PR introduce a breaking change?

• Yes
• No

Other information

This change improves documentation accuracy and developer experience. No functional or runtime behavior is affected.

[kamilmysliwiec]

lgtm