/usr/share/gtk-doc/html/gtk-faq is in libgtk2.0-doc 2.24.23-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/gtk-doc/html/../../doc/libgtk2.0-doc/faq
/usr/share/gtk-doc/html/../../doc/libgtk2.0-doc/faq