changing doc string conventions for deepsource best practices

[joshqsumner]

Describe your changes
Changed doc string conventions to align with best practices based on deepsource

Type of update
Is this an update to documentation

For the reviewer
See this page for instructions on how to review the pull request.

• PR functionality reviewed in a Jupyter Notebook
• All tests pass
• Test coverage remains 100%
• Documentation tested
• New documentation pages added to plantcv/mkdocs.yml
• Changes to function input/output signatures added to updating.md
• Code reviewed
• PR approved

[codecov]

Codecov Report

Merging #1391 (3be0ece) into main (996cd11) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1391   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          158       158           
  Lines         6939      6939           
=========================================
  Hits          6939      6939           

Flag	Coverage Δ
unittests	100.00% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
plantcv/plantcv/classes.py	100.00% <ø> (ø)
plantcv/plantcv/hyperspectral/write_data.py	100.00% <ø> (ø)
plantcv/plantcv/roi/roi_methods.py	100.00% <ø> (ø)
plantcv/plantcv/segment_image_series.py	100.00% <ø> (ø)
plantcv/plantcv/threshold/threshold_methods.py	100.00% <ø> (ø)