Add example in documentation that show show to test Vuex Store

[gkatsanos]

As in https://github.com/eddyerburgh/chapter-6/blob/master/src/store/__tests__/actions.spec.js , could you include a small use case/example on how to do simple Vuex store testing?

[lmiller1990]

I'm interested in contributing to this. I've been doing a lot of testing stuff with Vuex lately (from methods, to mocks the responses and seeing how things change in components etc), do you have anything specific in mind?

[gkatsanos]

Same here. I'm still not 100% confident I can document this as also the library is evolving but already I've built up some skills.

[lmiller1990]

If you just want help testing your store let me know @gkatsanos , I have done a lot of this kind of thing lately. I will be writing more about this in the coming weeks too, you can see here for more info or just get in touch and I can help you out.

[eddyerburgh]

I believe this is covered mostly in test-with-vuex. I think that section could be cleaned up though to be more clear