Avoid a shadowy variable on code example

[cyrilf]

Avoid the login variable to be shadowed in the example.

On the sagas.js file of the README example we can see:

import { login } from './actions'; // importing our action

and then

function* handleLoginSaga(action) {
  const { login, password } = action.payload;

So the login action is shadowed by the login from the payload.
Meaning that at the line yield put(login.success()); our code won't be happy.

Hope it helps :seedling: