/usr/share/gtk-doc/html/ is in libclutter-gtk-1.0-doc 1.4.4-3ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gtk-doc/html/clutter-gtk-1.0/
/usr/share/gtk-doc/html/clutter-gtk-1.0/GtkClutterActor.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/GtkClutterEmbed.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/GtkClutterWindow.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/annotation-glossary.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/ch01.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/ch02.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/ch03.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/clutter-gtk-1.0-Utility-Functions.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/clutter-gtk-1.0.devhelp2
/usr/share/gtk-doc/html/clutter-gtk-1.0/cluttergtk-glossary.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/cluttergtk-object-hierarchy.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/cluttergtk-object-index.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/cluttergtk-objects.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/home.png
/usr/share/gtk-doc/html/clutter-gtk-1.0/index.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/index.sgml
/usr/share/gtk-doc/html/clutter-gtk-1.0/ix01.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/ix02.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/ix03.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/ix04.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/left.png
/usr/share/gtk-doc/html/clutter-gtk-1.0/license.html
/usr/share/gtk-doc/html/clutter-gtk-1.0/right.png
/usr/share/gtk-doc/html/clutter-gtk-1.0/style.css
/usr/share/gtk-doc/html/clutter-gtk-1.0/up.png