DOC: config: Add section about name format for maps and ACLs

DOC: config: Add section about name format for maps and ACLs

Maps and list of ACLs can now reference something else than regular files
and can have prefix to set the type of the list (file, virutal file or
optional file). So, the configuration manual was updated accordingly.

The section 2.7. about name format for maps and ACLs was added (the former
2.7. sections with some examples was moved to 2.8.) and references to map or
ACLs files were updated.