/usr/share/doc/libxmlsec1-nss/README is in libxmlsec1-nss 1.2.20-2ubuntu4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libxmlsec1-nss/../libxmlsec1/README
/usr/share/doc/libxmlsec1-nss/../libxmlsec1/README