DNF 简中翻译补完

[Tommy He]

刚把 dnf 的简体中文翻译补完了，也是迁移到 Zanata 之后的首次补完，毕竟自己挖的坑含着泪也要填平对不对？

包括以下几个组件：

dnf: https://fedora.zanata.org/iteration/view/dnf/master/languages/zh-CN

dnf-plugins-core:
https://fedora.zanata.org/iteration/view/dnf-plugins-core/master/languages/z...

dnf-plugins-extras:
https://fedora.zanata.org/iteration/view/dnf-plugins-extras/master/languages...

dnf-plugin-system-upgrade:
https://fedora.zanata.org/iteration/view/dnf-plugin-system-upgrade/master/la...

求 Review，求反馈

黑日白月