Documentation minor bug fixes

[HaleySchuhl]

Describe your changes
Two doc bug fixes. Typo in pcv.roi2mask doc page and fix the parameter name in updating.md for pcv.flood_fill which has the plural points parameter now.

Type of update
Is this a:

• Bug fix
• Update to documentation

Associated issues

• closes roi2mask documentation needs updating #1371

Additional context
Add any other context about the problem here.

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 #1372 (402a14a) into main (d8ae17f) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1372   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          156       156           
  Lines         6878      6878           
=========================================
  Hits          6878      6878           

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

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Files	Coverage Δ
plantcv/plantcv/floodfill.py	100.00% <ø> (ø)