Fix bold font (#69)

Author: aaabramov

README.md

@@ -160,7 +160,7 @@ A: yes. Say you want to change `kafka1` port to `12345` (only relevant lines are
       KAFKA_ADVERTISED_LISTENERS: LISTENER_DOCKER_INTERNAL://kafka1:19092,LISTENER_DOCKER_EXTERNAL://${DOCKER_HOST_IP:-127.0.0.1}:12345
 ```
 
-**Q: Kafka is using a lot of disk space for testing. Can I reduce it?
+**Q: Kafka is using a lot of disk space for testing. Can I reduce it?**
 
 A: yes. This is for testing only!!! Reduce the KAFKA_LOG_SEGMENT_BYTES to 16MB and the KAFKA_LOG_RETENTION_BYTES to 128MB