find_color_card typo fix, move "label" param into correct function

[HaleySchuhl]

Describe your changes
Update doc page so that the label parameter is included while calling find_color_card rather than create_color_card_mask.

Type of update
Is this a:

• typo fix

Associated issues

Additional context
Add any other context about the problem here.

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• 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
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[codecov]

Codecov Report

Merging #1202 (af30be1) into main (58777cb) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main     #1202   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files          141       141           
  Lines         6024      6024           
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  Hits          6024      6024           

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

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