This file is indexed.

/usr/share/help/oc/gnome-terminal/index.docbook is in gnome-terminal-data 3.6.2-0ubuntu1.

This file is owned by root:root, with mode 0o777.

It is a symlink to /usr/share/help/oc/gnome-terminal/../../../help-langpack/oc/gnome-terminal/index.docbook