Document free Groq primary + NIM backup setup

Author: Rohan5commit

README.md

@@ -11,6 +11,19 @@ The AI that roasts your codebase so your teammates don't have to.
 pip install roast-my-code
 ```
 
+## Free LLM Setup (Recommended)
+
+Use Groq as primary (free tier), and NVIDIA NIM as backup.
+
+```bash
+export GROQ_API_KEY="your-groq-key"
+export NVIDIA_NIM_API_KEY="your-nim-key"
+```
+
+Default model choices in this project:
+- Primary: `llama-3.3-70b-versatile` (Groq)
+- Backup: `microsoft/phi-4-mini-instruct` (NIM)
+
 ## Usage
 
 ```bash
@@ -19,10 +32,17 @@ roast https://github.com/user/repo
 roast ./my-project --no-llm --output report.html
 ```
 
+Provider controls:
+
+```bash
+roast ./my-project --provider groq --model llama-3.3-70b-versatile
+roast ./my-project --provider auto --backup-provider nim --backup-model microsoft/phi-4-mini-instruct
+```
+
 ## Demo
 
 [demo.gif]
 
 ## Contributing
 
-Contributions are welcome. Open an issue for bugs/ideas, then submit a PR with tests for behavior changes.
+Contributions are welcome. Open an issue for bugs/ideas, then submit a PR with tests for behavior changes.