Add noRd to the code

[sambhavnoobcoder]

• quick fix to omit rd files out of the total roxygen code

Description

Added @noRd tag to the .create_folds function to prevent generation of Rd file for this internal function.

Motivation and Context

This change is required to prevent the generation of unnecessary Rd files for internal functions, which aligns with the project's documentation practices. It addresses the issue of Rd files being generated for non-exported functions.

Review Time Estimate

• Immediately
• Within one week
• When possible

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)

Checklist:

• My change requires a change to the documentation.
• My name is in the list of CITATION.cff
• I have updated the CHANGELOG.md.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.