Add solutions to last two exercises in episodes/exercise.md

[chennesy]

How could the content be improved?

The "Practice" and "Discussion" exercises at the end of the episode should have solutions to help instructors and provide self-paced learners with examples of how to solve these computational thinking challenges.

Which part of the content does your suggestion apply to?

https://librarycarpentry.org/lc-computational-thinking/exercise.html#practice