/usr/share/help/sl/fdl/index.docbook is in gnome-desktop3-data 3.18.2-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/help/sl/fdl/../../../help-langpack/sl/fdl/index.docbook
/usr/share/help/sl/fdl/../../../help-langpack/sl/fdl/index.docbook