/usr/lib/ghc-doc/hoogle/libghc-stringprep-doc.txt is in libghc-stringprep-doc 1.0.0-5build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-stringprep-doc/html/stringprep.txt