/usr/lib/ghc-doc/hoogle/wai-eventsource.txt is in libghc-wai-eventsource-doc 1.3.0.4-2build4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-wai-eventsource-doc/html/wai-eventsource.txt