small typo fix in docs/en/modules.md (vuejs#530)

Author: jbruni

docs/en/modules.md

@@ -83,7 +83,7 @@ const moduleA = {
 
 By default, actions, mutations and getters inside modules are still registered under the **global namespace** - this allows multiple modules to react to the same mutation/action type.
 
-If you want your modules to be more self-contained or resuable, you can mark it as namespaced with `namespaced: true`. When the module is registered, all of its getters, actions and mutations will be automatically namespaced based on the path the module is registered at. For example:
+If you want your modules to be more self-contained or reusable, you can mark it as namespaced with `namespaced: true`. When the module is registered, all of its getters, actions and mutations will be automatically namespaced based on the path the module is registered at. For example:
 
 ``` js
 const store = new Vuex.Store({