Document URL: 
https://docs.openshift.com/container-platform/3.5/install_config/aggregate_logging.html#aggregated-fluentd

Section Number and Name: 
Having Fluentd Use the Systemd Journal as the Log Source

Describe the issue: 
Reading of this is misleading. As its says by default fluentd reads from /var/log/containers/* for container logs. 

But in 3.5 docker defaults to journald so really by default fluentd will read from journal 

```
https://docs.openshift.com/container-platform/3.5/release_notes/ocp_3_5_release_notes.html

RHBA-2017:0903 - atomic-openshift-utils Bug Fix and Enhancement Update

The default docker log driver has been changed to journald in order to provider higher performance and lower logging latency. (BZ#1388191)
```

** We should include a warning that container logs are only symlinked to  /var/log/container/*  if docker is using "json-file" 

** We should highlight that dockers defaults to use journald logging driver now in 3.5 or later.