DOCS 15948 fix example field backport 7.0 (#3461)

Author: gmiller-mdb

source/reference/operator/aggregation/changeStream.txt

@@ -115,10 +115,12 @@ the :dbcommand:`aggregate` command.
    var cur = db.names.aggregate( [
       { $changeStream: {} }
    ] )
-   cur.next()
 
-When the change stream detects a change, the ``next()`` method returns a change
-event notification.  For example:
+To open the cursor, run ``cur``. 
+
+When the change stream detects a change, the ``next()`` method returns
+a change event notification. For example, after running ``cur.next()``, 
+MongoDB returns a document similar to the following:
 
 .. code-block:: json
    :copyable: false
@@ -142,5 +144,5 @@ event notification.  For example:
    }
 
 For more information on change stream notifications, see :ref:`Change Events
-<change-events>`
+<change-events>`.