Add documentation on how to use redux-dag-history and dag-history-component

[jimmy-guo]

Excited to play around with this in my project, but it is not obvious to me how I should use redux-dag-history and dag-history-component. Would it be possible to add some documentation and/or examples?

[darthtrevino]

You're absolutely right about the docs, I'll put some work in there. You can run the example by executing:
yarn install then yarn start. It should start up a simple app at localhost:8080 that demonstrates usage of the components and middleware.