Fix overindented docstrings

[nfahlgren]

Describe your changes
deepsource.io identified several docstrings that were overindented.

Type of update
Is this a: minor code quality improvement

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 #901 (20a0773) into master (6021db7) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #901   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          141       141           
  Lines         6006      6006           
=========================================
  Hits          6006      6006           

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

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

Impacted Files	Coverage Δ
plantcv/plantcv/crop.py	100.00% <ø> (ø)
plantcv/plantcv/hyperspectral/_avg_reflectance.py	100.00% <ø> (ø)
...antcv/plantcv/hyperspectral/_inverse_covariance.py	100.00% <ø> (ø)
...lantcv/plantcv/hyperspectral/extract_wavelength.py	100.00% <ø> (ø)
plantcv/plantcv/morphology/_iterative_prune.py	100.00% <ø> (ø)
plantcv/plantcv/morphology/analyze_stem.py	100.00% <ø> (ø)
plantcv/plantcv/morphology/find_branch_pts.py	100.00% <ø> (ø)
plantcv/plantcv/morphology/find_tips.py	100.00% <ø> (ø)
plantcv/plantcv/morphology/prune.py	100.00% <ø> (ø)
plantcv/plantcv/morphology/segment_angle.py	100.00% <ø> (ø)
... and 16 more