Write a how-to to configure a Cluster without Redis

Now that Nuxeo is usable with Kafka for the WorkManager and Invalidations, Redis is not necessary in some Cluster configuration (read-only LDAP users for instance).

This Redis-free documentation should describe how to configure Nuxeo to have:

• TransientStore based on KeyValueProvider in MongoDB
• Invalidations based on StreamPubSubProvider in Kafka
• WorkManager based on StreamWorkManager in Kafka

Because of the hybrid side of this configuration, it is not possible to have it with templates in the default distribution.