/usr/lib/ghc-doc/hoogle/semigroups.txt is in libghc-semigroups-doc 0.9-3build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-semigroups-doc/html/semigroups.txt