Merge pull request #28 from kazupon/fix/typo

fix typo

docs/en/api.md

@@ -64,7 +64,7 @@ const store = new Vuex.Store({ ...options })
   - type: `Boolean`
   - default: `false`
 
-    Force the Vuex store into strict mode. In strict mode any mutations to Vuex state outside of mutation handlers will throw en Error.
+    Force the Vuex store into strict mode. In strict mode any mutations to Vuex state outside of mutation handlers will throw an Error.
 
     [Details](strict.md)
 

docs/en/forms.md

@@ -6,7 +6,7 @@ When using Vuex in strict mode, it could be a bit tricky to use `v-model` on a p
 <input v-model="obj.message">
 ```
 
-Assuming `obj` is a computed property that returns an Object from the store, the `v-model` here will attempt to directly mutate `obj.message` when the user types in the input. In strict mode, this will result in en error because the mutation is not performed inside an explicit Vuex mutation handler.
+Assuming `obj` is a computed property that returns an Object from the store, the `v-model` here will attempt to directly mutate `obj.message` when the user types in the input. In strict mode, this will result in an error because the mutation is not performed inside an explicit Vuex mutation handler.
 
 The "Vuex way" to deal with it is binding the `<input>`'s value and call an action on the `input` or `change` event: