[DOCS] Adds max_page_search_size to data frame transform pivot proper…

…ties (#44126)

docs/reference/data-frames/apis/transformresource.asciidoc

@@ -79,8 +79,8 @@ pivot function `group by` fields and the aggregation to reduce the data.
 ===== {api-definitions-title}
 
 `aggregations` or `aggs`::
-(object) Defines how to aggregate the grouped data. The following composite
-aggregations are supported:
+  (object) Defines how to aggregate the grouped data. The following composite
+  aggregations are supported:
 +
 --
 * {ref}/search-aggregations-metrics-avg-aggregation.html[Average]
@@ -101,15 +101,21 @@ composite aggregations. See
 --
 
 `group_by`::
-(object) Defines how to group the data. More than one grouping can be defined
-per pivot. The following groupings are supported:
+  (object) Defines how to group the data. More than one grouping can be defined
+  per pivot. The following groupings are supported:
 +
 --
 * {ref}/search-aggregations-bucket-composite-aggregation.html#_terms[Terms]
 * {ref}/search-aggregations-bucket-composite-aggregation.html#_histogram[Histogram]
 * {ref}/search-aggregations-bucket-composite-aggregation.html#_date_histogram[Date Histogram]
 --
 
+`max_page_search_size`::
+  (integer) Defines the initial page size to use for the composite aggregation 
+  for each checkpoint. If circuit breaker exceptions occur, the page size is
+  dynamically adjusted to a lower value. The minimum value is `10` and the
+  maximum is `10,000`. The default value is `500`.
+
 [[data-frame-transform-example]]
 ==== {api-examples-title}