--Update setup.py attribution link

[jturner65]

Motivation and Context

This PR just updates the link to the source attribution/explanation behind our setup.py file, ( Building and testing a hybrid Python/C++ package ) which had broken some time ago.

How Has This Been Tested

No tests - just a comment link.

Types of changes

• Docs change / refactoring / dependency upgrade
• 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)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.