chore(doc): add update_time config description

_config.icarus.yml

@@ -130,6 +130,8 @@ article:
         fold: unfolded
     # Whether to show estimated article reading time
     readtime: true
+    # Whether to show updated time. For "auto", shows article update time only when page.updated is set and it is different from page.date
+    update_time: false
     # Article licensing block
     licenses:
         Creative Commons:

source/_posts/en/Configuring-Theme.md

@@ -321,6 +321,27 @@ article:
     readtime: true
 {% endcodeblock %}
 
+### Update Time
+
+To show an update time of an article, set `updated` time in the article's front-matter:
+
+{% codeblock post.md lang:yaml %}
+title: Getting Started with Icarus
+updated: 2020-04-01 00:00:00
+---
+Post content...
+{% endcodeblock %}
+
+Then, set `update_time` to `true` in the `article` section of your theme configuration file:
+
+{% codeblock _config.icarus.yml lang:yaml %}
+article:
+    update_time: true
+{% endcodeblock %}
+
+You may also set `update_time` to `false` to hide update time for all articles, or `auto`
+to hide update time when it is the same as the article publication time.
+
 ### Article Licensing
 
 You can show a section at the end of your posts/pages describing the licensing of your work.

source/_posts/zh-CN/Configuring-Theme.md

@@ -320,6 +320,27 @@ article:
     readtime: true
 {% endcodeblock %}
 
+### 文章更新时间
+
+若要显示文章的更新时间，请在文章的front_matter中设置`updated`时间：
+
+{% codeblock post.md lang:yaml %}
+title: Icarus快速上手
+updated: 2020-04-01 00:00:00
+---
+Post content...
+{% endcodeblock %}
+
+然后，将主题配置文件的`article`部分的`update_time`设置为`true`：
+
+{% codeblock _config.icarus.yml lang:yaml %}
+article:
+    update_time: true
+{% endcodeblock %}
+
+你也可以将`update_time`设置为`false`来隐藏所有文章的更新时间，或设置为`auto`而在文章的更新时间
+与发布时间相同时隐藏更新时间。
+
 ### 文章许可协议
 
 你可以在你的文章/页面的底部展示你的作品的使用许可，许可链接可以是文字或者图标。