/usr/lib/ghc-doc/hoogle/libghc-hstringtemplate-doc.txt is in libghc-hstringtemplate-doc 0.8.3-4build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-hstringtemplate-doc/html/HStringTemplate.txt