docs: fix broken NYC dataset download link

[tresende]

PR instructions

1. Describe your PR right below:

This PR fixes a broken download link in the Hello Timescale tutorial.
The link for the NYC Taxi dataset was pointing to an old blob storage URL and has been updated to the current official Timescale assets location.

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2. Add label for the earliest DB version your changes apply to -->> DB 2.0+ (applies to all currently supported versions, since this is docs-only)

3. If you are changing page names or in-page anchors, you must update the
   page-index.js file

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4. Please add at least one content reviewer. If you don't add an
   additional reviewer with knowledge about the area you are writing about,
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5. If this is in response to a posted GitHub issue, please add "Fixes <issue #>"
   below so that it's referenced (i.e. "Fixes Switch API command list function order to alphabetical #122")

6. If you are making simple corrections, reviewers may add comments to your
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   request/review cycles for simple changes. Make sure to address these
   comments (i.e. with changes) before your PR is ready to merge

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6. Feel free to delete these instructions in your PR message after everything
   else is filled out

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Additional notes:

Additional notes:
Simple correction in tutorials/tutorial-hello-timescale.md to fix a broken link:

Before: https://timescaledata.blob.core.windows.net/datasets/nyc_data.tar.gz

After: https://assets.timescale.com/docs/downloads/nyc_data.tar.gz

The default reviewers (CODEOWNERS) are added to each PR. They will
primarily be reviewing on formatting, not content. You only need ONE of them
to approve in order to merge your PR

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