/usr/lib/ghc-doc/hoogle/libghc-hashtables-doc.txt is in libghc-hashtables-doc 1.2.1.0-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-hashtables-doc/html/hashtables.txt