修订完hierarchical-DI

public/docs/ts/latest/guide/hierarchical-dependency-injection.jade

@@ -50,6 +50,9 @@ block includes
    You won't notice the difference and
    your mental model should be that every component has its own injector.
    
+   组件的注入器可能是一个组件树中更高级的祖先注入器的*代理*。
+   但这只是提升效率的实现细节，我们不用在乎这点差异，在你的脑海里只要想象成每个组件都有自己的注入器就可以了。
+
 :marked
   Consider this guide's variation on the Tour of Heroes application .
   At the top is the `AppComponent` which has some sub- components.