message: update injection docs
diff: The default behavior for the plugin is to forcebly inject a validator instaance for each component, which means each component has its own validator scope, that made sharing error messages between components relatively hard depending on your case.
  -You can turn the default inject false by providing `inject` option set to false in the plugin installation:
  +You can rely on Vue's [Provide/Inject API](https://vuejs.org/v2/api/#provide-inject) for this case, here is how it works:
  -```js
  -import Vue from 'vue';
  -import VeeValidate from 'vee-validate';
  -
  -Vue.use(VeeValidate, { inject: false });
  -```
  -
  -This will make the plugin stop instantiating a new validator for each component instance, and will instead rely on Vue's [Provide/Inject API](https://vuejs.org/v2/api/#provide-inject), here is how it works:
  -
  -By default the root Vue instance will be the only one to have a `Validator` instance, child components can further choose to either inject the parent's validator or request a new one.
  +By default the root Vue instance will be the only one to have a `Validator` instance, child components can further choose to either inject the parents tree validator or request a new one.
  Here is how to request the parent's validator instance:
  @@ -33,6 +24,7 @@ export default {
  > If the first parent isn't able to provide a validator instance, the API will traverse the tree upwards looking for a parent that can.
  +
  Here is how to request a new validator instance for the component by setting a `$validates` property on the component constructor options:
  ```js
  @@ -42,4 +34,15 @@ export default {
  };
  ```
  +You may also want to stop all automatic injections, and control when a components gets the ability to validate:
  +
  +```js
  +import Vue from 'vue';
  +import VeeValidate from 'vee-validate';
  +
  +Vue.use(VeeValidate, { inject: false });
  +```
  +
  +This will make the plugin stop instantiating a new validator for each component instance.
  +
  The `errorBag` and the `fields` objects will be also shared along with the validator, they will not be injected if the component does not have a validator instance.
  