What

This MR restructures a paragraph in the Getting Started with Octez tutorial, more specifically the section mentioned in the title.

Why

The paragraph refers and uses a contract that is available in the repo without explicitly saying so and later give the contract.

How

Restructured the paragraph to make things more natural and flowing. Added a command to download the said contract.

Manually testing the MR

Build the doc
Make sure the paragraph flows naturally.
Test the introduced command.

Checklist

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