Merge in "04-iteration"

Merge branch "04-iteration" into "develop"

Summary of the merged in commits:
 * 6385153e: Add review and exercises for notebook 04
 * 2c8ff65f: Adjust content overview in README.md
 * a91aea1f: Add initial version of notebook 04
 * 250aa092: Streamline previous content
 * 84e08d06: Move FizzBuzz exercise from chapter 01 to 03