Adding simple rgb tutorial to the tutorial gallergy

[annacasto]

Describe your changes
Adding a simple RGB workflow to the tutorial gallery. This tutorial is a straight-forward computer vision workflow and contains references to other workflows with options for more complexity.

Type of update
Is this a:

• New feature or feature enhancement

Associated issues
None

Additional context

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

[deepsource-io]

Here's the code health analysis summary for commits 8e34132..f6d1781. View details on DeepSource ↗.

Analysis Summary

Analyzer	Status	Summary	Link
Python	✅ Success		View Check ↗
Test coverage	✅ Success		View Check ↗

Code Coverage Report

Metric	Aggregate	Python
Branch Coverage	100%	100%
Composite Coverage	99.7%	99.7%
Line Coverage	99.7%	99.7%

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[annacasto]

Keely, I updated the index.ipynb notebook with the optional color correction step, so it should be all set for final review now.

[k034b363]

Looks good to me, just one typo to fix before the histogram (says "Creating a histogram of pixel insenity"). I also might suggest, since this is supposed to be super basic, that it would be helpful to include something like "you must do math to get the height and width of the ROI".

[annacasto]

Fixed typos and added some more context

[annacasto]

Fixed the title of the tutorial and added Workflow Inputs

[HaleySchuhl]

WorkflowInputs error resolve with re-running from the top, and maybe extra buttons (since binder is inconsistently functional)

[HaleySchuhl]

There's an error on the Workflow_Inputs part, but I believe it just needs to be re-ran and then it'll be good.

[nfahlgren]

@annacasto could you rerun the notebook and sync it to the tutorial repo? Currently it is rendered with an error:

Changes addressed