shutdown: add Chinese translation

pages.zh/osx/shutdown.md

@@ -0,0 +1,19 @@
+# shutdown
+
+> 关闭并重新启动系统.
+
+- 立即关机:
+
+`shutdown -h now`
+
+- 立即休眠:
+
+`shutdown -s now`
+
+- 立即重启:
+
+`shutdown -r now`
+
+- 倒计时 5 分钟重启:
+
+`shutdown -r +{{5}}`