Updates doc strings to use imperative writing style

[bryangalindo]

Minor doc string updates to keep uniform doc string writing style (i.e., imperative). Also, I wanted to introduce a small PR to get comfortable with the PR flow since I'm a new contributor.

Changes

Updates examples/polars/my_functions.py doc strings.

How I tested this

Ran all unit tests locally successfully.

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.