docs: clarify style precedence

[7nik]

Small clarifying about the style directive precedence.

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Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint

[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-svelte-16158-svelte.vercel.app/

[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@16158