added v-bind to example (vuejs#907)

Added `v-bind` to the Multiple Values example for consistency

Author: Paul Verbeek-Mast

src/v2/guide/class-and-style.md

@@ -200,5 +200,5 @@ When you use a CSS property that requires [vendor prefixes](https://developer.mo
 Starting in 2.3 you can provide an array of multiple (prefixed) values to a style property, for example:
 
 ``` html
-<div :style="{ display: ['-webkit-box', '-ms-flexbox', 'flex'] }">
+<div v-bind:style="{ display: ['-webkit-box', '-ms-flexbox', 'flex'] }">
 ```