/usr/lib/ghc-doc/hoogle/doctest.txt is in libghc-doctest-doc 0.9.10-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-doctest-doc/html/doctest.txt
/usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-doctest-doc/html/doctest.txt