streamline color correction in both notebooks

[HaleySchuhl]

Describe your changes

• adds usage of pcv.transform.auto_correct_color
• moved some comments to markdown from code comments
• adjust some plotting parameters

Type of update
Is this a:

• Workflow update
• Update to documentation (markdown/code comments)

Associated issues
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• Changes reviewed
• Workflow/Documentation updates made to both index.ipynb and index-Colab.ipynb
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