clamav freshclam - how to provide /etc config in general

[Christopher Chmielewski <christopherchmielewski@fastmail.com>]

Hello Guix Hackers :)

I'm new to Guix and I ran into the following error running the freshclam 
command:

ERROR: Can't open/parse the config file /etc/clamav/freshclam.conf

Now I understand that the error is that the config file is not present 
in /etc. However I figure that there is a "guix-way" of providing this 
config file instead of just creating it in /etc (which would be lost on 
reboot).

So my question is more general. How do you provide config files for 
software that expects it to be located in /etc? Is there a best practice?

Thanks,

Chris