[MINOR][SQL] Some errors in the notes.

## What changes were proposed in this pull request?

When using ordinals to access linked list, the time cost is O(n).

## How was this patch tested?

Existing tests.

Closes apache#23280 from CarolinePeng/update_Two.

Authored-by: CarolinPeng <00244106@zte.intra>
Signed-off-by: Sean Owen <sean.owen@databricks.com>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/package.scala

@@ -101,7 +101,7 @@ package object expressions  {
       StructType(attrs.map(a => StructField(a.name, a.dataType, a.nullable, a.metadata)))
     }
 
-    // It's possible that `attrs` is a linked list, which can lead to bad O(n^2) loops when
+    // It's possible that `attrs` is a linked list, which can lead to bad O(n) loops when
     // accessing attributes by their ordinals. To avoid this performance penalty, convert the input
     // to an array.
     @transient private lazy val attrsArray = attrs.toArray

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

@@ -93,7 +93,7 @@ abstract class LogicalPlan
   /**
    * Optionally resolves the given strings to a [[NamedExpression]] using the input from all child
    * nodes of this LogicalPlan. The attribute is expressed as
-   * as string in the following form: `[scope].AttributeName.[nested].[fields]...`.
+   * string in the following form: `[scope].AttributeName.[nested].[fields]...`.
    */
   def resolveChildren(
       nameParts: Seq[String],