Fix mini typo

[anthager]

Correct "daetaset" to "dataset" in the introduction.md

Description

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Fix typo in introduction.md

Affected Dependencies

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None

How has this been tested?

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Not applicable

Checklist

• [x] I have followed the Contribution Guidelines and Code of Conduct
• [ ] I have commented my code following the OpenMined Styleguide (not applicable)
• [ ] I have labeled this PR with the relevant Type labels (Im not able to set a label, but I would like to set the "Documentation" label)
• [ ] My changes are covered by tests (not applicable)

[chinmayshah99]

Nice, catch. thanks!