Missing CONTRIBUTING.md, README links to it but file doesn't exist


The README has a Contributing section (line 153) that links to CONTRIBUTING.md, but no such file exists in the repo

```
We welcome contributions to CrewAI-GUI! Please refer to our CONTRIBUTING.md for guidelines on:
- Submitting pull requests
- Reporting issues
- Requesting new features
```


Either create a CONTRIBUTING.md with actual guidelines, or remove the broken link from the README.