docs: add Windows setup guide and fix for 'tree' and 'pdbfixer' import errors (resolves #1047)

[praharsh777]

This PR resolves #1047, where users encounter: ModuleNotFoundError: No module named 'tree' This is caused by the dm-tree package not being properly installed or recognized on some Windows environments.

✅ What I Did Installed dm-tree manually using "" pip install --force-reinstall --no-cache-dir dm-tree "" to resolve the tree module error.

Resolved a follow-up ModuleNotFoundError for pdbfixer by installing it via GitHub: pip install git+https://github.com/openmm/pdbfixer.git

Verified both test cases in run_alphafold_test.py passed successfully on Windows 10 with Python 3.12.6.

Added a step-by-step Windows installation guide to README.md to help other users avoid this issue.