/usr/lib/ghc-doc/hoogle/libghc-icalendar-doc.txt is in libghc-icalendar-doc 0.4.0.3-2build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-icalendar-doc/html/iCalendar.txt