RHEL 8, RH124, Chapter 11, Section 7, has an error - it references a man page that doesn't exist:
First: systemd-journald.conf isn't the name of the configuration file that controls (amongst other things) the persistency of the systemd journals. That happens to be journald.conf
Second: systemd-journald.conf(5) isn't a man page, as seen here:
The man page is journald.conf(5):
I want to say that the man page used to be named that in RHEL 7, but I don't have a machine handy to check with. Seems like a valid bug.
I do, and it doesn't exist in v7 either.
Even so... as it doesn't exist in RHEL 8, it shouldn't appear in the RHEL 8 material.