DOCS-579 batchSize doc fix spelling

Author: kay-kim

source/reference/method/cursor.batchSize.txt

@@ -36,6 +36,6 @@ cursor.batchSize()
 
    This operation will set the batch size for the results of a query
    (i.e. :method:`find() <db.collection.find()>`) to ``10``. The
-   effects of this operation do not effect the output in the
+   effects of this operation do not affect the output in the
    :program:`mongo` shell, which always iterates over the first 20
    documents.