docs: update animated sprite example

[billyjacoby]

I spent far longer than I would care to admit getting this working yesterday, and I think a clearer example would drastically help that.

Description of change

Fixes:

Pre-Merge Checklist

• [ ] Tests and/or benchmarks are included
• [ ] Documentation is changed or added
• [ ] Lint process passed (npm run lint)
• [ ] Tests passed (npm run test)

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