Update instructions.md to reflect actual map

[codecakes]

The documentation claims:

Clothing items are stored as a map:

%{
  item_name: "Descriptive Name",
  price: 99.00,
  base_color: "red"
}

While the actual structure is like this in the tests:

%{
  item_name: "Descriptive Name",
  price: 99.00,
  color: "Ochre Red",
  base_color: "red"
}

[github-actions[bot]]

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Automated comment created by PR Commenter 🤖.

[angelikatyborska]

Thanks!