DOCSP-21058 fix backport error (#860)

Author: Dave

source/reference/operator/aggregation/first.txt

@@ -48,8 +48,6 @@ value depends on the order of the documents coming into pipeline. To
 guarantee a defined order, the :pipeline:`$group` pipeline stage should
 follow a :pipeline:`$sort` stage.
 
-.. include:: /includes/note-group-and-window-behavior.rst
-
 Missing Values
 ~~~~~~~~~~~~~~