Fix documentation of 'array.encoding' option

I am having below error when trying load data from mongodb to kafka
config file

name=s-kafka
connector.class=io.debezium.connector.mongodb.MongoDbConnector
tasks.max=1
database.list=mongo1.backend.alpha.redmart.com:27017
connection.url=mongo1.backend.alpha.redmart.com:27017
mongodb.hosts=mongo1.backend.alpha.redmart.com:27017
mongodb.name=oship
collection.whitelist=dmdb.shipments_kafka
database.whitelist=dmdb
converter.class=org.apache.kafka.connect.json.JsonConverter
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=false
value.converter.schemas.enable=false
internal.value.converter=org.apache.kafka.connect.json.JsonConverter
#plugin.path=share/java/
transforms=unwrap
transforms.unwrap.type=io.debezium.connector.mongodb.transforms.UnwrapFromMongoDbEnvelope
transforms.unwrap.array.encoding=struct
transforms.unwrap.flatten.struct=true
#transforms.unwrap.flatten.struct.delimiter=_

Error:

[2018-09-27 14:06:59,707] ERROR The 'array.encoding' value 'struct' is invalid: Value must be one of array, document (io.debezium.connector.mongodb.transforms.UnwrapFromMongoDbEnvelope:1817)
[2018-09-27 14:06:59,707] ERROR Failed to start task mship2-0 (org.apache.kafka.connect.runtime.Worker:455)
org.apache.kafka.connect.errors.ConnectException: Unable to validate config.
at io.debezium.connector.mongodb.transforms.UnwrapFromMongoDbEnvelope.configure(UnwrapFromMongoDbEnvelope.java:241)
at org.apache.kafka.connect.runtime.ConnectorConfig.transformations(ConnectorConfig.java:251)
at org.apache.kafka.connect.runtime.Worker.buildWorkerTask(Worker.java:495)
at org.apache.kafka.connect.runtime.Worker.startTask(Worker.java:451)
at org.apache.kafka.connect.runtime.distributed.DistributedHerder.startTask(DistributedHerder.java:873)
at org.apache.kafka.connect.runtime.distributed.DistributedHerder.access$1600(DistributedHerder.java:111)
at org.apache.kafka.connect.runtime.distributed.DistributedHerder$13.call(DistributedHerder.java:888)
at org.apache.kafka.connect.runtime.distributed.DistributedHerder$13.call(DistributedHerder.java:884)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)