Add Groq YAML configuration example #87

Description

Add a YAML config example for Groq (free tier, fast inference) to the examples directory.

What to do

1. Create examples/groq_config.yaml based on the pattern in existing YAML examples
2. Set provider to groq, model to llama-3.3-70b-versatile
3. Include a sample prompt and processing settings
4. Test with ondine process --config examples/groq_config.yaml --dry-run

Acceptance criteria

• New YAML config file in examples/
• Dry-run executes without errors