DOCS-12111: read pref and txns

Author: kay-kim

source/core/transactions.txt

@@ -256,22 +256,11 @@ Multi-document transactions are atomic:
   data changes made in the transaction are discarded without ever
   becoming visible.
 
-Read Preference
----------------
-
-.. include:: /includes/extracts/transactions-read-pref.rst
 
 .. _transaction-options:
 
-Transaction Options (Read Concern/Write Concern)
-------------------------------------------------
-
-.. code-block:: javascript
-
-   session.startTransaction( {
-      readConcern: { level: <level> },
-      writeConcern: { w: <value>, j: <boolean>, wtimeout: <number> } 
-   } );
+Transaction Options (Read Concern/Write Concern/Read Preference)
+----------------------------------------------------------------
 
 .. _txn-read-concern:
 
@@ -355,6 +344,12 @@ transaction commit at the transaction start.
   :readconcern:`"majority"` read concern provides no guarantees that
   read operations read majority-committed data.
 
+Read Preference
+~~~~~~~~~~~~~~~
+
+.. include:: /includes/extracts/transactions-read-pref.rst
+
+
 Transactions and Locks
 ----------------------