Testing Practice: Explicitly state difference from example

[nekosoffy]

Because

I think that for the benefit of clarity, if what the assignment proposes is different from the reference that is linked, it should be stated explicitly to leave no ambiguity if it was intentional or an oversight.

This PR

• Adds some detail to one of the assignment's bullet points that specifies that it should be done differently than what was shown (keep original lettercase instead of all uppercase).

Issue

Closes #XXXXX

Additional Information

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project curriculum contributing guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [x] If this PR addresses an open issue, it is linked in the Issue section
• [x] If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• [x] If any lesson files are included in this PR, they follow the Layout Style Guide

[linkonsat]

I think that could make it a bit more confusing. The instructions specify what the conditions to follow and an example. It came off as a bit confusing to add that to me as I could see someone reading it and being confused if they were supposed to use the link for the first cipher test. As they should get the same result as the examples below the article and they would benefit from asking how to achieve it on the Discord. I do appreciate it however!