[Mecha Munch Management] Fixed typos in Instructions, Introduction, & Stub File

[BethanyG]

• Corrected dict typo in exercise stub to iterable (test data has both nested tuples and lists)
• Corrected LIFO ref in code example for Introduction.md Sorting a Dictionary section.
• Corrected code examples in instructions.md task 3 Update Recipe "Ideas" section.

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