Update svelte.md

[seb-lean]

The tip use yarn or pnpm is related to the npx command, not npm command.

Changes

Moves a tip closer to relevant command example.

Testing

No tests added or done, as I just moved some text.

Docs

This is a fix to documentation

[changeset-bot]

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Latest commit: ada524a

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[seb-lean]

The updated tip position:

https://snowpack-git-fork-seb-lean-patch-1-pikapkg.vercel.app/tutorials/svelte