update description

Author: kiszk

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

@@ -291,11 +291,11 @@ case class ArrayTransform(
  */
 // scalastyle:off line.size.limit
 @ExpressionDescription(
-  usage = """_FUNC_(expr, func) - Sorts the input array in ascending order. The elements of the
-    input array must be orderable. Null elements will be placed at the end of the returned
-    array. Since 3.0.0 this function also sorts and returns the array based on the given
-    comparator function. The comparator will take two arguments
-    representing two elements of the array.
+  usage = """_FUNC_(expr, func) - Sorts the input array. If func is omitted, sort
+    in ascending order. The elements of the input array must be orderable. Null elements
+    will be placed at the end of the returned. Since 3.0.0 this function also sorts and
+    and returns the array based on the given comparator function. The comparator will
+    take two arguments representing two elements of the array.
     It returns -1, 0, or 1 as the first element is less than, equal to, or greater
     than the second element. If the comparator function returns other
     values (including null), the function will fail and raise an error.