/usr/lib/ghc-doc/hoogle/strict-concurrency.txt is in libghc-strict-concurrency-doc 0.2.4.1-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-strict-concurrency-doc/html/strict-concurrency.txt