Here are the steps to complete the assignment:
1. Create RDDs to filter each file for lines containing "Spark":
val readme = sc.textFile("README.md").filter(_.contains("Spark"))
val changes = sc.textFile("CHANGES.txt").filter(_.contains("Spark"))
2. Perform WordCount on each:
val readmeCounts = readme.flatMap(_.split(" ")).map((_,1)).reduceByKey(_ + _)
val changesCounts = changes.flatMap(_.split(" ")).map((_,1)).reduceByKey(_ + _)
3. Join the two RDDs:
val joined = readmeCounts.join(changes