Add "In the wild" section to README with typeclasses.dhall example

[Copilot]

This PR adds an "In the wild" section to the README.md that showcases real-world usage of this GitHub Actions workflow for deploying Dhall documentation.

The new section includes a comprehensive example featuring the typeclasses.dhall repository, which demonstrates typical usage patterns:

• Repository link: Direct reference to the project using this workflow
• Workflow configuration: Link to their actual workflow file showing how they implement the reusable workflow
• Generated documentation: Link to the live documentation site at https://nikita-volkov.github.io/typeclasses.dhall/
• Usage context: Description of how they configure the workflow (using src/ directory, typeclasses package name, and automatic triggers)

This addition provides users with a concrete, working example that they can reference when implementing their own documentation workflows, helping them understand both the configuration and the expected output.

The section is strategically placed after the "Configuration Options" section and before "Troubleshooting" to provide a practical example that reinforces the configuration concepts just covered.

Fixes #9.

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