Remove ambiguous link anchors for logging { file } statement

Remove ambiguous link anchors for logging { file } statement

Unfortunatelly logging and zone blocks use file statements with
different semantics but the same name.

There is no sane way to disambiguate them in text, so let's remove the
link anchor from logging so we can link to the file statement in zone.

My assumption is that linking to logging { file } is very unlikely
because logging is self-contained in one block but zone config is all
over the place.