Docsp 15085 aggregations in updates (#192)

Co-authored-by: kyuan-mongodb <[email protected]>

Author: biniona-mongodb

source/fundamentals/crud/write-operations/change-a-document.txt

@@ -59,6 +59,15 @@ and their usage </reference/operator/update-field/>`.
 The update operators apply only to the fields associated with them in your
 update document.
 
+.. note:: Aggregation Pipelines in Update Operations
+
+   If you are using MongoDB Version 4.2 or later, you can use aggregation
+   pipelines made up of a subset of aggregation stages in update operations. For
+   more information on the aggregation stages MongoDB supports in
+   aggregation pipelines used in update operations, see our tutorial on building
+   :manual:`updates with aggregation pipelines </tutorial/update-documents-with-aggregation-pipeline/>`. 
+
+
 Example
 ~~~~~~~