/usr/share/doc/libfftw3-bin/README is in libfftw3-bin 3.3.3-7ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libfftw3-bin/../libfftw3-double3/README
/usr/share/doc/libfftw3-bin/../libfftw3-double3/README