/usr/lib/ghc-doc/hoogle/libghc-kan-extensions-doc.txt is in libghc-kan-extensions-doc 5.0.2-1build3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-kan-extensions-doc/html/kan-extensions.txt