Special key filter presets require quotes

[dpass]

The docs (http://vuejs.org/guide/events.html#The_Special_key_Filter) say you can specify a key filter like this:

<input v-on="keyup:submit | key enter">`

However, as per the filter syntax change in v0.12.0 (https://github.com/yyx990803/vue/releases/tag/0.12.0) the key specifier must be surrounded in quotes like this:

<input v-on="keyup:submit | key 'enter'">

The docs should be changed to reflect this necessity

[yyx990803]

Thanks for catching this!