DOCSP-45876 Add parallel operations callout (#952)

* add callout

* fix typo

* update method reference

* edit note

* update include

* remove extra file

(cherry picked from commit ab64365)

Author: stephmarie17

source/fundamentals/transactions.txt

@@ -208,6 +208,8 @@ the Convenient Transaction API:
 To see a fully runnable example that uses this API, see the
 :ref:`node-usage-convenient-txn` usage example.
 
+.. sharedinclude:: dbx/transactions-parallelism.rst
+
 .. _nodejs-transaction-settings:
 
 Transaction Options