remove unnecessary md

2.4.0.md

@@ -1,16 +0,0 @@
-### New
-
-- New helper method `createNamesapcedHelpers`: a helper-generator that generates namespaced `mapXXX` helpers for you:
-
-  ``` js
-  const { mapState, mapActions } = createNamespacedHelpers('some/nested/module')
-  // everything generated by mapState and mapActions are bound to the module.
-  ```
-
-  See [docs](https://vuex.vuejs.org/en/modules.html#binding-helpers-with-namespace) for more info.
-
-  (@riophae via #800)
-
-### Misc
-
-- Various typing and assertion improvements.