Address reviewer feedback: comprehensive improvements to advanced GRPO recipe

- Add direct link to existing HuggingFace GRPO cookbook example
- Fix CUDA device setting for Colab compatibility (auto-detect instead of hardcoded)
- Add comprehensive explanations throughout all recipe sections
- Enhance with detailed comparison table showing differences from basic example
- Improve GPU setup with memory information and fallback instructions
- Add detailed LoRA configuration explanations and parameter analysis
- Expand dataset preparation with GSM8K background and format details
- Detail multi-reward system design for mathematical reasoning approach
- Optimize training configuration with Colab-specific memory settings
- Enhance testing and evaluation with detailed response analysis
- Make notebook fully end-to-end recipe focused for cookbook standards
- Address all reviewer feedback comprehensively for cookbook contribution

Author: behroozazarkhalili