/usr/lib/ghc-doc/hoogle/system-fileio.txt is in libghc-system-fileio-doc 0.3.11-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-system-fileio-doc/html/system-fileio.txt