README.md in embulk-output-cassandra-0.2.0 vs README.md in embulk-output-cassandra-0.3.0

@@ -65,10 +65,12 @@
 - **username**: cluster username (string, default: `null`)
 - **password**: cluster password (string, default: `null`)
 - **cluster_name**: cluster name (string, default: `null`)
 - **keyspace**: target keyspace name (string, required)
 - **table**: target table name (string, required)
+- **mode**: insert or update (string, default: `"insert"`)
 - **if_not_exists**: Add "IF NOT EXISTS" to INSERT query (boolean, default: `false`)
+- **if_exists**: Add "IF EXISTS" to UPDATE query (boolean, default: `false`)
 - **ttl**: Add "TTL" to INSERT query (integer, default: `null`)
 - **idempotent**: Treat INSERT query as idempotent (boolean, default: `false`)
 - **connect_timeout**: Set connect timeout millisecond (integer, default: `5000`)
 - **request_timeout**: Set each request timeout millisecond (integer, default: `12000`)