Refine default freenetrc values.

Trailing slash on freenetRoot led to "//" in resulting paths which -
while it doesn't have a practical effect - looks annoying.

The fred dir makes more sense as "fred" than "fred-official" when it is
a clone of fred-staging and also has a fred-official remote. (As in
setup-release-environment.)
Create directory containing IP file; document.

Those who host the IP to country database have requirements for
avoiding being overloaded.