title: correct usage of reduce-reducers
body: <p>I don't understand what <a href="https://github.com/acdlite/reduce-reducers" rel="noreferrer">reduce-reducers</a> is meant for. Should it be used in the case that I have 2 reducer functions containing the same action? </p>
  
  <pre><code>function reducerA(state, action){
     switch(action.type):
         ...
         case 'SAME_ACTION': {...state, field: state.field+1}
  }
  
  function reducerB(state, action){
     switch(action.type):
         ...
         case 'SAME_ACTION': {...state, field: state.field*2}
  }
  </code></pre>
  
  <p>So if I call <code>reduceReducer</code> on <code>reducerA</code> and <code>reducerB</code> and action 'SAME_ACTION' is invoked for <code>{field: 0}</code> then I would have a next state <code>{field: 2}</code>?</p>
  
  <p>Also it seems to me that it kind of concatenates reducers (meaning merging them under one key). </p>
  
  <p>Am I right or does <code>reduceReducer</code> serve a different purpose?</p>