Add Intersection Wrong example from lecture 3

src/main/scala/lecture3/03_IntersectionWrong.scala

+package lecture3
+
+import scala.collection._
+import scala.collection.parallel.CollectionConverters.IterableIsParallelizable
+import org.scalameter._
+
+// TODO : THIS DOES NOT COMPILE
+def intersection(a: GenSet[Int], b: GenSet[Int]): Set[Int] =
+  val result = mutable.Set[Int]()
+  for (x <- a) if (b contains x) result += x
+  result
+
+@main def intersectionWrong =
+  val seqres = intersection((0 until 1000).toSet, (0 until 1000 by 4).toSet)
+  val parres = intersection((0 until 1000).par.toSet, (0 until 1000 by 4).par.toSet)
+  log(s"Sequential result - ${seqres.size}")
+  log(s"Parallel result - ${parres.size}")
+
+