[URL]
https://github.com/openshift/openshift-docs/blob/enterprise-4.7/modules/cluster-logging-collector-legacy-fluentd.adoc

[ISSUE]
In the example for secure_forward and the definition is wrong (the definition is for in the input secure_forward as it's possible to see here [1], but, it's not for the output definition.

[SUGGESTION]
Replace in the two examples this:
~~~
self_hostname fluentd.example.com
~~~

And this:
~~~
self_hostname <common-name> (1)
~~~

By this:

~~~
self_hostname ${hostname} (1)
~~~

And change this text:

~~~
Specify the default value of the auto-generated certificate common name (CN).
~~~

By this:
~~~
Client hostname
~~~

You can read more about this latest here [2].

This is a regression and it was reported for OCP 4.4 in the past and it was fixed in tha version:

• https://bugzilla.redhat.com/show_bug.cgi?id=1844449

[1] https://docs.fluentd.org/v/0.12/input/secure_forward
[2] https://docs.fluentd.org/v/0.12/output/secure_forward