Add answers to Batch Processing Bronze Reflect Questions

[kelseymok]

At the end of the exercise, there is a "Reflect" section

• Add Spark UI screenshots of where people can see how many in-memory partitions have been created (and explanation) as a result of the repartition
• Add Spark UI screenshots of how much time the write took (and explanation) - this is due to parquet taking a while to write

[syed-tw]

Added the reflect section with answers in the solution notebook. Not able to add the screenshots for now so just added the explanations.