Add Function type to props (#2026) (#1527)

* Add Function type to props

* add Promise contstructor prop type

Author: vuejs-jp-bot

src/v2/guide/components-props.md

@@ -42,7 +42,9 @@ props: {
   likes: Number,
   isPublished: Boolean,
   commentIds: Array,
-  author: Object
+  author: Object,
+  callback: Function,
+  contactsPromise: Promise // or any other constructor
 }
 ```