docs: Make "unquoted" example actually unquoted

[danawoodman]

Example should show that unquoted values work, but shows example with a quote 😄

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• [ ] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
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• [ ] This message body should clearly illustrate what problems it solves.
• [ ] Ideally, include a test that fails without this PR but passes with it.

Tests and linting

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

[geoffrich]

Is there a chance of prettier/autoformat "fixing" this change and putting the quotes back?