/usr/share/doc/qtdeclarative5-particles-plugin/changelog.Debian.gz is in qtdeclarative5-particles-plugin 5.5.1-2ubuntu6.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/qtdeclarative5-particles-plugin/../qml-module-qtquick-particles2/changelog.Debian.gz