fix docs description

I think this 'action' maybe is not the action in Vuex? Maybe using 'mutation' in docs is more specific
I check the englinsh docs, and it's the same word 'action'...
Maybe I misunderstand the mean

docs: fix docs desc in forms part

docs/guide/forms.md

@@ -10,7 +10,7 @@ When using Vuex in strict mode, it could be a bit tricky to use `v-model` on a p
 
 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:
+The "Vuex way" to deal with it is binding the `<input>`'s value and call a method on the `input` or `change` event:
 
 ``` html
 <input :value="message" @input="updateMessage">

docs/zh/guide/forms.md

@@ -10,7 +10,7 @@
 
 假设这里的 `obj` 是在计算属性中返回的一个属于 Vuex store 的对象，在用户输入时，`v-model` 会试图直接修改 `obj.message`。在严格模式中，由于这个修改不是在 mutation 函数中执行的, 这里会抛出一个错误。
 
-用“Vuex 的思维”去解决这个问题的方法是：给 `<input>` 中绑定 value，然后侦听 `input` 或者 `change` 事件，在事件回调中调用 action:
+用“Vuex 的思维”去解决这个问题的方法是：给 `<input>` 中绑定 value，然后侦听 `input` 或者 `change` 事件，在事件回调中调用一个方法:
 
 ``` html
 <input :value="message" @input="updateMessage">