docs: add mutiple covers

docs/cover.md

@@ -26,9 +26,9 @@ Set `coverpage` to **true**, and create a `_coverpage.md`:
 
 > A magical documentation site generator.
 
-- Simple and lightweight (~18kB gzipped)
-- No statically built html files
-- Multiple themes
+* Simple and lightweight (~18kB gzipped)
+* No statically built html files
+* Multiple themes
 
 [GitHub](https://github.com/QingWei-Li/docsify/)
 [Get Started](#docsify)
@@ -49,8 +49,51 @@ The background color is generated randomly by default. You can customize the bac
 [Get Started](#quick-start)
 
 <!-- background image -->
+
 ![](_media/bg.png)
 
 <!-- background color -->
+
 ![color](#f0f0f0)
 ```
+
+## Coverpage as homepage
+
+Normal, the coverpage and the homepage appear at the same time. Of course, you can also separate the coverpage by [onlyCover option](configuration.md#onlycover).
+
+## Multiple covers
+
+If your docs site is in more than one language, it may be useful to set multiple covers.
+
+For example, your docs structure is like this
+
+```text
+.
+└── docs
+    ├── README.md
+    ├── guide.md
+    ├── _coverpage.md
+    └── zh-cn
+        ├── README.md
+        └── guide.md
+        └── _coverpage.md
+```
+
+Now, you can set
+
+```js
+window.$docsify = {
+  coverpage: ['/', '/zh-cn/']
+};
+```
+
+Or a special file name
+
+```js
+window.$docsify = {
+  coverpage: {
+    '/': 'cover.md',
+    '/zh-cn/': 'cover.md'
+  }
+};
+```