This prevents file/directory clashes. Example: when we have a `tags` item, and a `tags/foo` item, there will be a clash since the store creates: - a file `store/tags`; - a file `store/tags/foo`. The second file requires the first file to be a directory. We simply solve this by adding a suffix to all store files, so it becomes: - a file `store/tags.hakyllstore`; - a file `store/tags/foo.hakyllstore`.