Docs: Polish Getting Started section (#80402)
Please merge this PR first: https://github.com/vercel/next.js/pull/80401
- Reorder pages. Group routing + rendering + data fetching, and UI
concerns (styling, css, images, etc)
- Update page titles to use keyword instead of "How to" for search
results
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Co-authored-by: graphite-app[bot] <96075541+graphite-app[bot]@users.noreply.github.com>
