Docs: Add Data Security Guide (#80249)
Closes: https://linear.app/vercel/issue/DOC-4678/guide-data-security
Please merge this PR first: https://github.com/vercel/next.js/pull/80242
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Co-authored-by: graphite-app[bot] <96075541+graphite-app[bot]@users.noreply.github.com>
Co-authored-by: Joseph <joseph.chamochumbi@vercel.com>
