/usr/share/help/bg/zenity/index.page is in zenity-common 3.8.0-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/help/bg/zenity/../../../help-langpack/bg/zenity/index.page
/usr/share/help/bg/zenity/../../../help-langpack/bg/zenity/index.page