/usr/share/help/el/zenity/intro.page is in zenity-common 3.18.1.1-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/help/el/zenity/../../../help-langpack/el/zenity/intro.page
/usr/share/help/el/zenity/../../../help-langpack/el/zenity/intro.page