Direct user to publish ./package/ directory instead of ./

[brev]

After running svelte-package (via create-svelte), the user is supposed to
run: npm publish package/. However, it is easy to accidentally run
npm publish on the wrong directory out of habit. With this change,
when the user accidentally tries to publish the ./ directory, they will be
directed to publish the ./package/ directory instead.

In case it is useful, thanks.

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[changeset-bot]

🦋 Changeset detected

Latest commit: eed3a68

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
create-svelte	Patch

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[dummdidumm]

Thank you!