/usr/lib/ghc-doc/hoogle/x509-validation.txt is in libghc-x509-validation-doc 1.4.6-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-x509-validation-doc/html/x509-validation.txt