Docs: Document `global-not-found` (#81803)
Closes:
https://linear.app/vercel/issue/DOC-4873/document-global-not-found
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Co-authored-by: graphite-app[bot] <96075541+graphite-app[bot]@users.noreply.github.com>
Co-authored-by: Jiachi Liu <inbox@huozhi.im>
