/usr/share/doc/gccgo-8-multilib-x86-64-linux-gnux32 is in gccgo-8-multilib-x86-64-linux-gnux32 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gcc-8-x86-64-linux-gnux32-base