DOCS-12189: serverStatus transactions.prepared metrics

Author: kay-kim

source/reference/command/serverStatus.txt

@@ -1289,7 +1289,12 @@ transactions
       "currentOpen" : <NumberLong>,
       "totalAborted" : <NumberLong>,
       "totalCommitted" : <NumberLong>,
-      "totalStarted" : <NumberLong>
+      "totalStarted" : <NumberLong>,
+      "totalPrepared" : <NumberLong>,
+      "totalPreparedThenCommitted" : <NumberLong>,
+      "totalPreparedThenAborted" :  <NumberLong>,
+      "currentPrepared" :  <NumberLong>,
+      "oldestActiveOplogEntryTimestamp" : <Timestamp>
    },
 
 .. serverstatus:: transactions
@@ -1393,6 +1398,42 @@ transactions
 
    .. versionadded:: 4.0.2
 
+.. serverstatus:: transactions.totalPrepared
+
+   The total number of transactions in prepared state on this server
+   since the :binary:`mongod <bin.mongod>` process's last startup.
+
+   .. versionadded:: 4.2
+
+.. serverstatus:: transactions.totalPreparedThenCommitted
+
+   The total number of transactions that were prepared and committed on
+   this server since the :binary:`mongod <bin.mongod>` process's last
+   startup.
+
+   .. versionadded:: 4.2
+
+.. serverstatus:: transactions.totalPreparedThenAborted
+
+   The total number of transactions that were prepared and aborted on
+   this server since the :binary:`mongod <bin.mongod>` process's last
+   startup.
+
+   .. versionadded:: 4.2
+
+.. serverstatus:: transactions.currentPrepared
+
+   The current number of transactions in prepared state on this server.
+
+   .. versionadded:: 4.2
+
+.. serverstatus:: transactions.oldestActiveOplogEntryTimestamp
+
+   The optime of the oldest oplog entry associated with an active
+   transaction.
+
+   .. versionadded:: 4.2
+
 .. _server-status-wiredTiger:
 
 wiredTiger