/usr/lib/ghc-doc/hoogle/fast-logger.txt is in libghc-fast-logger-doc 0.3.3-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-fast-logger-doc/html/fast-logger.txt