Add an extra unit for python paths

The first assignment is tripping some of the students who are unfamiliar with how python paths work. There are 2 common scenarios:

- They use strings for file paths. It works on their Windows machine, but when it's time to submit a CI workflow, it fails since the workflow is on a Linux OS.
- They use absolute file paths to locate data files, which stumps the CI workflow as it has a different file system.

This could be either a small video or text explaining how to refer to file paths in a way to works on every machine and OS.

Review the first assignment and its CI workflow to identify where students encounter Windows-specific or absolute paths. Create either a short text explanation or video showing portable ways to refer to data files across machines and operating systems; done means both reported scenarios are addressed.

Written by the indexing model from the issue text.