/usr/lib/ghc-doc/hoogle/libghc-double-conversion-doc.txt is in libghc-double-conversion-doc 2.0.2.0+ds1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-double-conversion-doc/html/double-conversion.txt