/usr/share/doc/libsaml2-dev/README.txt is in libsaml2-dev 2.6.1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libsaml2-dev/../libsaml9/README.txt
/usr/share/doc/libsaml2-dev/../libsaml9/README.txt