DOCSP-45868: Parallel operations admonition (#81)

(cherry picked from commit 4cad443)

Author: mcmorisi

source/write/transactions.txt

@@ -170,6 +170,15 @@ completes the following actions:
 
       Transaction successful!
 
+.. sharedinclude:: dbx/transactions-parallelism.rst
+
+   .. replacement:: driver-specific-content
+
+      If you're using {+mdb-server+} v8.0 or later, you can perform
+      write operations on multiple namespaces within a single transaction by using
+      bulk write operations. For more information, see the :ref:`<c-bulk-write>`
+      guide.
+
 Additional Information
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