Rewrite readme to use URL instead of relative path to the logo

[rahlk]

Fix logo rendering issue on PyPI by replacing relative image path with a raw GitHub URL in the README.

Motivation and Context

PyPI does not support relative image paths in README.md. The logo (./docs/assets/logo.png) failed to render on the project page. This fix ensures the logo displays correctly by pointing to the raw image URL on GitHub.

How Has This Been Tested?

• Verified rendering locally via a Markdown preview
• Uploaded the updated package to TestPyPI to confirm correct logo rendering

Breaking Changes

None

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the Codellm-Devkit Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

This change improves visual presentation and polish of the package on PyPI. Using raw GitHub URLs is a standard workaround for PyPI’s lack of support for relative paths in long descriptions.