Modify create_hnsw_index

[ahill187]

Description

In this PR, I have renamed knn_struct variables to hnsw_index, since there are no structs in Python so this doesn't really make sense. Also, they use the HNSW algorithm, not the KNN algorithm.

Type of Change

• 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 not work as expected)
• Documentation (updated docstrings or README files)
• Tests (added new tests or modified current test suite)
• Refactoring (changes in the design of the code that don't change the functionality)

Tests

None.

Linked PRs / Issues

ahill187#27

Checklist:

• I have performed a self-review of my code
• I have documented my code with appropriate docstrings
• I have made corresponding changes to the documentation / README files
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes