/usr/lib/ghc-doc/hoogle/markov-chain.txt is in libghc-markov-chain-doc 0.0.3.2-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-markov-chain-doc/html/markov-chain.txt