Update cn.php

Hello @serghey-rodin.
Update:
  1. L155 -- Add keywords that are missing. (Comparative en are missing)
  2. L199-202 -- Replaced by a more accurate translation.

In addition, in here I explained cn and en differences: outroll/vesta#514 (comment)

Author: myrevery

web/inc/i18n/cn.php

@@ -152,6 +152,7 @@
     'User Directories' => '用户目录',
     'Template' => '模板',
     'Web Template' => 'Web模板',
+    'Backend Template' => '后台模板',
     'Proxy Template' => '代理模板',
     'DNS Template' => 'DNS模板',
     'Web Domains' => '网站域名',
@@ -195,10 +196,10 @@
     'User' => '用户',
     'Host' => '主机',
     'Charset' => '编码',
-    'Min' => '分钟',
-    'Hour' => '小时',
-    'Day' => '天',
-    'Month' => '月',
+    'Min' => '几分',
+    'Hour' => '几点',
+    'Day' => '几号',
+    'Month' => '月份',
     'Day of week' => '星期几',
     'local' => '本地',
     'Run Time' => '运行时间',