grammar tweak

Author: Cladis

source/core/aggregation-pipeline.txt

@@ -51,7 +51,7 @@ For example usage of the aggregation pipeline, consider
 Pipeline Expressions
 --------------------
 
-Some pipeline stages takes a pipeline expression as its operand.
+Some pipeline stages take a pipeline expression as its operand.
 Pipeline expressions specify the transformation to apply to the input
 documents. Expressions have a :doc:`document </core/document>`
 structure and can contain other :ref:`expression
@@ -145,4 +145,4 @@ See :ref:`aggregation-pipeline-sharded-collection`.
       /core/aggregation-pipeline-limits
       /core/aggregation-pipeline-sharded-collections
       Example with ZIP Code Data </tutorial/aggregation-zip-code-data-set>
-      Example with User Preference Data </tutorial/aggregation-with-user-preference-data>
+      Example with User Preference Data </tutorial/aggregation-with-user-preference-data>