DOCS-14840 5.0.4 setWindowFields restriction updates (mongodb#5977)

* DOCS-14840 5.0.4 setWindowFields restriction updates

* Update source/reference/operator/aggregation/setWindowFields.txt

Co-authored-by: jeff-allen-mongo <jeffrey.allen@10gen.com>

Co-authored-by: jeff-allen-mongo <jeffrey.allen@10gen.com>

Author: ianf-mongodb

source/reference/operator/aggregation/setWindowFields.txt

@@ -242,6 +242,12 @@ Restrictions
 
 Restrictions for the :pipeline:`$setWindowFields` stage:
 
+- Starting in MongoDB 5.0.4, the :pipeline:`$setWindowFields` 
+  stage cannot be used:
+
+  - Within :doc:`transactions </core/transactions>`.
+  - With :readconcern:`"snapshot"` read concern.
+
 - :ref:`sortBy <setWindowFields-sortBy>` is required for:
 
   - :ref:`Rank <setWindowFields-rank-operators>` and :ref:`order