DOCSP-26395 Fixes split delimiter (#2801) (#2823)

* DOCSP-26395 Fixes split delimiter

* Fixes text

* Fixes text

Author: kennethdyer

source/reference/operator/aggregation/split.txt

@@ -162,7 +162,7 @@ descending order. It has five pipeline stages:
 - The :pipeline:`$project` stage produces documents with two fields,
   ``qty`` (integer) and ``city_state`` (array). The ``$split``
   operator creates an array of strings by splitting the ``city``
-  field, using a space (``" "``) as a delimiter.
+  field, using a comma followed by a space (``", "``) as a delimiter.
 
 - The :pipeline:`$unwind` stage creates a separate record for each
   element in the ``city_state`` field.