Update azure-synapse-diagnostic-emitters-azure-eventhub.md

Author: kaiyuezhou

articles/synapse-analytics/spark/azure-synapse-diagnostic-emitters-azure-eventhub.md

@@ -54,6 +54,7 @@ For more description of the parameters, you can refer to [Azure EventHub configu
 | `spark.synapse.diagnostic.emitter.<destination>.secret`                     | Optional. The Azure Eventhub instance connection string. This field should match this pattern `Endpoint=sb://<FQDN>/;SharedAccessKeyName=<KeyName>;SharedAccessKey=<KeyValue>;EntityPath=<PathName>` |
 | `spark.synapse.diagnostic.emitter.<destination>.secret.keyVault`            | Required if `.secret` is not specified. The [Azure Key vault](../../key-vault/general/overview.md) name where the secret (connection string) is stored.                                                                  |
 | `spark.synapse.diagnostic.emitter.<destination>.secret.keyVault.secretName` | Required if `.secret.keyVault` is specified. The Azure Key vault secret name where the secret (connection string) is stored.                                                                         |
+| `spark.synapse.diagnostic.emitter.<destination>.secret.keyVault.linkedService` | Optional. The Azure Key vault linked service name. When enabled in Synapse pipeline, this is necessary to obtain the secret from AKV. (Please make sure MSI has read permission on the AKV). |
 | `spark.synapse.diagnostic.emitter.<destination>.filter.eventName.match`     | Optional. The comma-separated spark event names, you can specify which events to collect. For example: `SparkListenerApplicationStart,SparkListenerApplicationEnd` |
 | `spark.synapse.diagnostic.emitter.<destination>.filter.loggerName.match`    | Optional. The comma-separated log4j logger names, you can specify which logs to collect. For example: `org.apache.spark.SparkContext,org.example.Logger` |
 | `spark.synapse.diagnostic.emitter.<destination>.filter.metricName.match`    | Optional. The comma-separated spark metric name suffixes, you can specify which metrics to collect. For example: `jvm.heap.used` |