[SPARK-12188][SQL][FOLLOW-UP] Code refactoring and comment correction in Dataset APIs

marmbrus This PR is to address your comment. Thanks for your review!

Author: gatorsmile <[email protected]>

Closes #10214 from gatorsmile/followup12188.

Author: gatorsmile

sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala

@@ -79,7 +79,7 @@ class Dataset[T] private[sql](
 
   /**
    * The encoder where the expressions used to construct an object from an input row have been
-   * bound to the ordinals of the given schema.
+   * bound to the ordinals of this [[Dataset]]'s output schema.
    */
   private[sql] val boundTEncoder = resolvedTEncoder.bind(logicalPlan.output)