l10n: zh_CN.po: translate 2 new, 3 fuzzy messages

Translate 2 new and 3 fuzzy messages came from git.pot update
in 75f7b4b (l10n: Update git.pot (5 new, 3 removed messages)).

Signed-off-by: Jiang Xin <worldhello.net@gmail.com>

Author: jiangxin