/usr/share/doc/gfortran-5-multilib-x86-64-linux-gnux32 is in gfortran-5-multilib-x86-64-linux-gnux32 5.5.0-12ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gcc-5-x86-64-linux-gnux32-base