Added friendly hint when message.max.bytes is configured too low.

rdkafka_broker.c

@@ -1244,7 +1244,8 @@ static int rd_kafka_recv (rd_kafka_broker_t *rkb) {
 		    rkbuf->rkbuf_len >
 		    rkb->rkb_rk->rk_conf.max_msg_size + 100) {
 			snprintf(errstr, sizeof(errstr),
-				 "Invalid message size %zd (0..%i)",
+				 "Invalid message size %zd (0..%i): "
+				 "increase message.max.bytes",
 				 rkbuf->rkbuf_len-4,
 				 rkb->rkb_rk->rk_conf.max_msg_size);
 			rkb->rkb_c.rx_err++;