/usr/lib/ghc-doc/hoogle/libghc-syb-with-class-doc.txt is in libghc-syb-with-class-doc 0.6.1.7-3build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-syb-with-class-doc/html/syb-with-class.txt