/redux-handle-async-events: introduce topic

[mdegani]

Explain what Effects is after learning redux: reducers are synchronous with pure functions (no side effcts), so how do we make HTTP requests or get user input? Naive solution of calling http in “fat action creator” and this leads us to a better solution: “effects” which handles our side effects.

[mdegani]

@rpdasilva please review the description of this story