/usr/lib/ghc-doc/hoogle/libghc-classy-prelude-doc.txt is in libghc-classy-prelude-doc 1.2.0.1-1build5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-classy-prelude-doc/html/classy-prelude.txt