docs: update code block filename in dynamic API context error page (#67000)
The filenames of the two code blocks on this page
https://nextjs.org/docs/messages/next-dynamic-api-wrong-context are
written as comment instead of using the `filename` prop.

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Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
Co-authored-by: Sam Ko <sam@vercel.com>