The full path name is in the file bley.conf.example, as this is the most likely end-user configuration.
In reality, we just get the string from the ConfigParser, and the open() call uses it.
So relative paths work just as well (and the test-suite uses them).

I'm assuming most people will install the package in preference to a github checkout.
I suppose that a package manager would install /etc/bley/bley.conf anyway, so the example file can be tailored to github users.