Fix markup in README

Author: mahendra

README.md

@@ -42,6 +42,7 @@ kafka.close()
 ```
 
 ## Keyed messages
+```python
 from kafka.client import KafkaClient
 from kafka.producer import KeyedProducer
 from kafka.partitioner import HashedPartitioner, RoundRobinPartitioner
@@ -51,7 +52,7 @@ kafka = KafkaClient("localhost", 9092)
 producer = KeyedProducer(kafka, "my-topic", partitioner=HashedPartitioner)
 producer.send("key1", "some message")
 producer.send("key2", "this methode")
-
+```
 
 ## Low level