Include converters + schema disable by default in docs

For Confluent, these elements need to be specified if you're using datagen to put data in.

Using REST and the UI also both work with these options so adding this in seems to be the most robust way to get someone started.

README.md

@@ -76,7 +76,10 @@ It is possible to use the connector as a plugin on Confluent Cloud as a [Custom
   "client.id": "Ably-Kafka-Connector",
   "channel": "#{topic}",
   "message.name": "#{topic}_message",
-  "client.key": "<YOUR_ABLY_API_KEY>"
+  "client.key": "<YOUR_ABLY_API_KEY>",
+  "key.converter": "org.apache.kafka.connect.converters.ByteArrayConverter",
+  "value.converter": "org.apache.kafka.connect.converters.ByteArrayConverter",
+  "value.converter.schemas.enable": "false"
 }
 ```
 7. When asked for an endpoint, enter `rest.ably.io:443:TCP`