Adds an additional example

[niallobrien]

Adds an example that explains how to use Vuex in the context of building a realtime app with Feathers.js on the backend.

[ktsn]

Hi, @niallobrien!
Thank you for your example, but please open a PR to https://github.com/vuejs/awesome-vue instead. It is the curated list for kind of this 😉

[yyx990803]

This looks like a decent example to include :)

[niallobrien]

Thank you. :)