/usr/lib/ghc-doc/hoogle/xml2html.txt is in libghc-xml2html-doc 0.2.0-3build4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-xml2html-doc/html/xml2html.txt