docs: fix outdated links

packages/docs/docs/theme/option-api.md

@@ -49,14 +49,14 @@ You probably don't need to use following options tagged with <Badge text="Danger
 - Type: `String`
 - Default: undefined
 
-HTML template path used in `dev` mode, default template see [here](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/app/index.dev.html)
+HTML template path used in `dev` mode, default template see [here](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/client/index.dev.html)
 
 ## ssrTemplate <Badge text="Danger Zone"/>
 
 - Type: `String`
 - Default: undefined
 
-HTML template path used in `build` mode, default template see [here](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/app/index.ssr.html)
+HTML template path used in `build` mode, default template see [here](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/client/index.ssr.html)
 
 **Also see:**
 

packages/docs/docs/zh/theme/option-api.md

@@ -47,14 +47,14 @@ module.exports = (themeConfig, ctx) => {
 - 类型: `String`
 - 默认值: undefined
 
-dev 模式下使用的 HTML 模板路径，默认模板见 [这里](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/app/index.dev.html)。
+dev 模式下使用的 HTML 模板路径，默认模板见 [这里](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/client/index.dev.html)。
 
 ## ssrTemplate <Badge text="Danger Zone"/>
 
 - 类型: `String`
 - 默认值: undefined
 
-build 模式下使用的 HTML 模板路径，默认模板见 [这里](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/app/index.ssr.html)。
+build 模式下使用的 HTML 模板路径，默认模板见 [这里](https://github.com/vuejs/vuepress/blob/master/packages/%40vuepress/core/lib/client/index.ssr.html)。
 
 **参考:**