DOCSP-29558 5.0 pushdown projection changes (#3189) (#3473)

* DOCSP-29558 5.0 pushdown projection changes

* IF feedback

* GH feedback

* punctuation

Author: ajhuh-mdb

source/release-notes/5.0.txt

@@ -439,6 +439,7 @@ Issues fixed:
 
 - :ref:`5.0.1-changelog`
 
+
 5.0.0 - Jul 13, 2021
 ~~~~~~~~~~~~~~~~~~~~
 
@@ -576,6 +577,14 @@ collections.
 
 See :ref:`lookup-uncorrelated-subquery`.
 
+``$sort`` Stage: Performance Improvements
+`````````````````````````````````````````
+
+Starting in MongoDB 5.0, the :term:`query optimizer` pushes down the results of 
+a :pipeline:`$project` stage into the :pipeline:`$sort` stage. As a result, 
+``$sort`` operations can require less RAM when used with the ``project`` stage 
+and avoid ``Sort exceeded memory limit`` errors. 
+
 Aggregation Metrics
 ```````````````````