/usr/share/doc/pd-markex/README is in pd-markex 0.85-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/pd-markex/../../../lib/pd/extra/markex/README.txt
/usr/share/doc/pd-markex/../../../lib/pd/extra/markex/README.txt