Update scaladoc for a field and move it to @param section.

Author: concretevitamin

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala

@@ -31,12 +31,11 @@ abstract class LogicalPlan extends QueryPlan[LogicalPlan] {
    * Estimates of various statistics.  The default estimation logic simply sums up the corresponding
    * statistic produced by the children.  To override this behavior, override `statistics` and
    * assign it a overriden version of `Statistics`.
+   *
+   * @param sizeInBytes Physical size in bytes. For leaf operators this defaults to 1, otherwise it
+   *                    defaults to the product of children's `sizeInBytes`.
    */
   case class Statistics(
-    /**
-     * Physical size in bytes. For leaf operators this defaults to 1, otherwise it is set to the
-     * product of children's `sizeInBytes`.
-     */
     sizeInBytes: Long = childrenStats.map(_.sizeInBytes).product
   )
   lazy val statistics: Statistics = new Statistics
@@ -108,7 +107,7 @@ abstract class LogicalPlan extends QueryPlan[LogicalPlan] {
 abstract class LeafNode extends LogicalPlan with trees.LeafNode[LogicalPlan] {
   self: Product =>
 
-  override lazy val statistics = Statistics(numTuples = 1L, sizeInBytes = 1L)
+  override lazy val statistics = Statistics(sizeInBytes = 1L)
 
   // Leaf nodes by definition cannot reference any input attributes.
   override def references = Set.empty