/usr/lib/ghc-doc/hoogle/hxt-http.txt is in libghc-hxt-http-doc 9.1.4-5build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-hxt-http-doc/html/hxt-http.txt