fix(docs): fix tailwind class name value

[abedshaaban]

When I copied this code snippet, the lg and md didn't work since my prettier format corrected it as "var(--radius)" thus adding " before and after the `

lg: `var(--radius)`,
md: `calc(var(--radius) - 2px)`,
sm: "calc(var(--radius) - 4px)"

[vercel]

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