/usr/share/doc/python-lxml-doc/html is in python-lxml-doc 3.5.0-1ubuntu0.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/python-lxml-doc/../python-lxml/html
/usr/share/doc/python-lxml-doc/../python-lxml/html