Remove Kafka from Infrastructure components list

Kafka is actually not deployed in kolla-ansible.

Change-Id: Icda9bfb3c264db9f7428f391a487c94739198e70

README.rst

@@ -100,8 +100,6 @@ Kolla-Ansible deploys containers for the following infrastructure components:
 - `HAProxy <http://www.haproxy.org/>`__ and
   `Keepalived <http://www.keepalived.org/>`__ for high availability of services
   and their endpoints.
-- `Kafka <http://kafka.apache.org/documentation/>`__ A distributed streaming
-  platform.
 - `MariaDB and Galera Cluster <https://mariadb.com/kb/en/mariadb/galera-cluster/>`__
   for highly available MySQL databases.
 - `Memcached <https://memcached.org/>`__ a distributed memory object caching system.