/usr/lib/ghc-doc/hoogle/fdo-notify.txt is in libghc-fdo-notify-doc 0.3.1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-fdo-notify-doc/html/fdo-notify.txt