/usr/share/doc/libboost-doc/HTML is in libboost1.62-doc 1.62.0+dfsg-5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libboost-doc/../libboost1.62-doc/HTML
/usr/share/doc/libboost-doc/../libboost1.62-doc/HTML