docs: update links (#1440)

Author: shigma

packages/docs/docs/guide/markdown.md

@@ -8,20 +8,7 @@ Headers automatically get anchor links applied. Rendering of anchors can be conf
 
 ### Internal Links
 
-Inbound links ending in `.md` or `.html` are converted to `<router-link>` for SPA navigation.
-
-Each sub-directory in your static site should contain a `README.md`. It will automatically be converted to `index.html`.
-
-::: tip
-When writing the relative path to a directory's `index.html`, don't forget to close it off with a `/`, otherwise you will get a 404. For example, use `/config/` instead of `/config`.
-:::
-
-If you want to link to another markdown file within a directory, remember to:
-
-1.  Append it with either `.html` or `.md`
-2.  Make sure the case matches since the path is case-sensitive
-
-#### Example
+Internal links are converted to `<router-link>` for SPA navigation. Also, every `README.md` or `index.md` contained in each sub-directory will automatically be converted to `index.html`, with corresponding url `/`.
 
 Given the following directory structure:
 
@@ -38,14 +25,24 @@ Given the following directory structure:
    └─ four.md
 ```
 
+And providing you are in `foo/one.md`:
+
 ```md
 [Home](/) <!-- Sends the user to the root README.md -->
 [foo](/foo/) <!-- Sends the user to index.html of directory foo -->
-[foo heading anchor](/foo/#heading) <!-- Anchors user to a heading in the foo README file -->
-[foo - one](/foo/one.html) <!-- You can append .html -->
-[foo - two](/foo/two.md) <!-- Or you can append .md -->
+[foo heading](./#heading) <!-- Anchors user to a heading in the foo README file -->
+[bar - three](../bar/three.md) <!-- You can append .md (recommended) -->
+[bar - four](../bar/four.html) <!-- Or you can append .html -->
 ```
 
+### Redirection for URLs <Badge text="1.0.0-alpha.37"/>
+
+VuePress supports redirecting to clean links. If a link `/foo` is not found, VuePress will look for a existing `/foo/` or `/foo.html`. Conversely, when one of `/foo/` or `/foo.html` is not found, VuePress will also try the other. With this feature, we can customize your website's urls with the official plugin [@vuepress/plugin-clean-urls](../plugin/official/plugin-clean-urls.md).
+
+::: tip
+Regardless of whether the permalink and clean-urls plugins are used, your relative path should be defined by the current file structure. In the above example, even though you set the path of `/foo/one.md` to `/foo/one/`, you should still access `/foo/two.md` via `./two.md`.
+:::
+
 ### External Links
 
 Outbound links automatically gets `target="_blank" rel="noopener noreferrer"`:

packages/docs/docs/zh/guide/markdown.md

@@ -8,20 +8,7 @@
 
 ### 内部链接
 
-内部的、并以 `.md` or `.html` 结尾的链接，将会被转换成 `<router-link>` 用于 SPA 导航。
-
-站内的每一个子文件夹都应当有一个 `README.md` 文件，它会被自动编译为 `index.html`。
-
-::: tip
-在链接到一个文件夹的 `index.html` 时，确保你的链接以 `/` 结尾，否则该链接将导致 404。比如，用 `/config/` 而不是 `/config`。
-:::
-
-如果你想要链接到另一个 markdown 文件：
-
-1. 确保链接以 `.html` 或 `.md` 结尾；
-2. 确保路径大小写正确，因为路径的匹配是大小写敏感的。
-
-#### 示例
+网站内部的的链接，将会被转换成 `<router-link>` 用于 SPA 导航。同时，站内的每一个文件夹下的 `README.md` 或者 `index.md` 文件都会被自动编译为 `index.html`，对应的链接将被视为 `/`。
 
 以如下的文件结构为例：
 
@@ -38,14 +25,24 @@
    └─ four.md
 ```
 
+假设你现在在 `foo/one.md` 中：
+
 ``` md
 [Home](/) <!-- 跳转到根部的 README.md -->
 [foo](/foo/) <!-- 跳转到 foo 文件夹的 index.html -->
-[foo heading anchor](/foo/#heading) <!-- 跳转到 foo/index.html 的特定 anchor 位置 -->
-[foo - one](/foo/one.html) <!-- 具体文件可以使用 .html 结尾 -->
-[foo - two](/foo/two.md) <!-- 也可以用 .md -->
+[foo heading](./#heading) <!-- 跳转到 foo/index.html 的特定标题位置 -->
+[bar - three](../bar/three.md) <!-- 具体文件可以使用 .md 结尾（推荐） -->
+[bar - four](../bar/four.html) <!-- 也可以用 .html -->
 ```
 
+### 链接的重定向 <Badge text="1.0.0-alpha.37"/>
+
+VuePress 支持重定向到干净链接。如果一个链接 `/foo` 找不到，VuePress 会自行寻找一个可用的 `/foo/` 或 `/foo.html`。反过来，当 `/foo/` 或 `/foo.html` 中的一个找不到时，VuePress 也会尝试寻找另一个。借助这种特性，我们可以通过官方插件 [@vuepress/plugin-clean-urls](../plugin/official/plugin-clean-urls.md) 定制你的网站路径。
+
+::: tip 注意
+无论是否使用了 permalink 和 clean-urls 插件，你的相对路径都应该依赖于当前的文件结构来定义。在上面的例子中，即使你将 `/foo/one.md` 的路径设为了 `/foo/one/`，你依然应该通过 `./two.md` 来访问 `/foo/two.md`。
+:::
+
 ### 外部链接
 
 外部的链接将会被自动地设置为  `target="_blank" rel="noopener noreferrer"`: