docs: fix wording in sass error comment

[Rohan5commit]

Related issue: N/A (trivial comment wording fix)

Fixes a wording typo in the CSS plugin by changing re-uses to reuses in an internal comment.

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• What is this PR solving? Write a clear and concise description. (comment wording typo only)
• Reference the issues it solves (e.g. fixes #123). (N/A)
• What other alternatives have you explored? (N/A for trivial typo fix)
• Are there any parts you think require more attention from reviewers? (No)
• Read the Contributing Guidelines at https://github.com/vitejs/vite/blob/main/CONTRIBUTING.md.
• Check that there isn't already a PR that solves the problem the same way.
• Update the corresponding documentation if needed. (Not needed for an internal comment fix)
• Include relevant tests that fail without this PR but pass with it. If the tests are not included, explain why. (Not run; comment-only change)

[Copilot]

Pull request overview

This PR makes a small wording correction in Vite’s CSS/Sass processing code by fixing a typo in an internal comment.

Changes:

• Update a comment in the SCSS error-normalization path to change “re-uses” → “reuses”.