/usr/share/doc/libgail-doc/html is in libgail-doc 2.24.30-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgail-doc/../../gtk-doc/html/gail-libgail-util
/usr/share/doc/libgail-doc/../../gtk-doc/html/gail-libgail-util