Update Chapter 4 "Part 1 completed!" page

[CorbanPendrak]

Description

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This pull request reformats the Chapter 4 "Part 1 completed!" page

Changes

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• Removes part 2 future post with reference to blog
• Adds list of topics covered
• Rewords final challenge paragraph

Purpose

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Since part 2 has already been added to the course, the part 2 reference is irrelevant. The list of topics covered more closely resembles the other pages closing the previous chapters. The final paragraph has been reworded to remove parentheses and simplify the instruction's convolutions.