Function Basics: Fix typo in assignment section

[attackersalt]

Fix typo in word 'articles' (change to 'article') in 5th reading of Assignment

Because

Fix typo

This PR

• Fixes typo in assignment section

Issue

Closes #29050

Additional Information

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
• 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
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
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