docs: remove dotenv method of loading environment variables

[teemingc]

The minimum Node version is Node 22 so we don't need to recommend using dotenv anymore. There's a built-in way to do it.

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 6f86583:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/6f86583c5c1c18d38e9520a487f6b707e6e72797

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16853

[changeset-bot]

⚠️ No Changeset found

Latest commit: 6f86583

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-16853-svelte.vercel.app/

[Nic-Polumeyv]

Yes!