/usr/lib/ghc-doc/hoogle/intervals.txt is in libghc-intervals-doc 0.7-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-intervals-doc/html/intervals.txt
/usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-intervals-doc/html/intervals.txt