Rest Spread is now at Stage 3 (#371)

https://github.com/sebmarkbage/ecmascript-rest-spread

docs/en/state.md

@@ -80,7 +80,7 @@ export default {
 
 ### Object Spread Operator
 
-Note that `mapState` returns an object. How do we use it in combination with other local computed properties? Normally, we'd have to use a utility to merge multiple objects into one so that we can pass the final object to `computed`. However with the [object spread operator](https://github.com/sebmarkbage/ecmascript-rest-spread) (which is a stage-2 ECMASCript proposal), we can greatly simplify the syntax:
+Note that `mapState` returns an object. How do we use it in combination with other local computed properties? Normally, we'd have to use a utility to merge multiple objects into one so that we can pass the final object to `computed`. However with the [object spread operator](https://github.com/sebmarkbage/ecmascript-rest-spread) (which is a stage-3 ECMASCript proposal), we can greatly simplify the syntax:
 
 ``` js
 computed: {