/usr/lib/ghc-doc/hoogle/unix-bytestring.txt is in libghc-unix-bytestring-doc 0.3.5.4-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-unix-bytestring-doc/html/unix-bytestring.txt