/usr/lib/ghc-doc/hoogle/haddock.txt is in libghc-haddock-doc 2.13.1-3build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-haddock-doc/html/haddock.txt