DOCSP-33122 fix ref (#5320) (#5341)

Author: jocelyn-mendez1

source/tutorial/perform-incremental-map-reduce.txt

@@ -204,7 +204,7 @@ The operation returns the following documents:
 Aggregation Alternative
 -----------------------
 
-As an alternative to map-reduce, you can use an :ref`aggregation
+As an alternative to map-reduce, you can use an :ref:`aggregation
 pipeline <aggregation-pipeline>` that combines :pipeline:`$group`
 and :pipeline:`$merge` stages to achieve the same result in a more
 flexible operation.