docs: add overflow to Vite CLI code block

[Evavic44]

Description

Add overflow-x: auto to the Vite CLI code block in the Vite 3.0 announcement page. This adds a horizontal scrollbar for viewers on mobile screens: (375 x 667) to be precise.

Reference Issue: #9383

Additional context

The property was added directly into the <pre> element found here. Not completely sure if that's the recommended way of doing it. I'm happy to take any corrections.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[patak-dev]

Thanks @Evavic44!

[sapphi-red]

👍