include @next in installation instructions for now

docs/en/installation.md

@@ -2,7 +2,7 @@
 
 ### Direct Download / CDN
 
-[https://unpkg.com/vuex](https://unpkg.com/vuex)
+[https://unpkg.com/vuex@next](https://unpkg.com/vuex@next)
 
 [Unpkg.com](https://unpkg.com) provides NPM-based CDN links. The above link will always point to the latest release on NPM. You can also use a specific version/tag via URLs like `https://unpkg.com/[email protected]`.
 
@@ -16,7 +16,7 @@ Include `vuex` after Vue and it will install itself automatically:
 ### NPM
 
 ``` bash
-npm install vuex
+npm install vuex@next
 ```
 
 When used with a module system, you must explicitly install the router via `Vue.use()`: