[D1] D1 HTTP API tutorial (#16412)

* Add D1 http tutorial

* Apply suggestions from code review

Co-authored-by: Max Rozen <3822106+rozenmd@users.noreply.github.com>

* Update src/content/docs/d1/tutorials/build-an-api-to-access-d1/index.mdx

Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>

* Finishing first review of the tutorial doc.

* Finishing first review of the tutorial doc.

* Clarifying language surrounding API_KEY.

* Minor grammar fix

* Improvements to clarity of the tutorial addressed in feedback.

* Fixing broken link

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Co-authored-by: Max Rozen <3822106+rozenmd@users.noreply.github.com>
Co-authored-by: Jun Lee <junlee@cloudflare.com>
Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>