Merge pull request reduxjs#516 from mindjuice/patch-21

Minor help text improvements

Author: gaearon

docs/api/combineReducers.md

@@ -1,8 +1,8 @@
 # `combineReducers(reducers)`
 
-As your app grows more complex, you’ll want to split your [reducing function](../Glossary.md#reducer) into separate different functions managing independent parts of the [state](../Glossary.md#state).
+As your app grows more complex, you’ll want to split your [reducing function](../Glossary.md#reducer) into separate functions, each managing independent parts of the [state](../Glossary.md#state).
 
-This helper turns an object whose values are different reducing functions into a single
+The `combineReducers` helper function turns an object whose values are different reducing functions into a single
 reducing function you can pass to [`createStore`](createStore.md).
 
 The resulting reducer calls every child reducer, and gather their results into a single state object. The shape of the state object matches the keys of the passed `reducers`.
@@ -13,7 +13,7 @@ The resulting reducer calls every child reducer, and gather their results into a
 
 #### Arguments
 
-1. `reducer` (*Object*): An object whose values correspond to different reducing functions that need to be combined into one. One handy way to obtain it is to use ES6 `import * as reducers` syntax, but you can also construct this object manually. See the notes below for some rules every passed reducer must follow.
+1. `reducers` (*Object*): An object whose values correspond to different reducing functions that need to be combined into one. One handy way to obtain it is to use ES6 `import * as reducers` syntax, but you can also construct this object manually. See the notes below for some rules every passed reducer must follow.
 
 #### Returns
 
@@ -29,7 +29,7 @@ Any reducer passed to `combineReducers` must satisfy these rules:
 
 * It may never return `undefined`. It is too easy to do this by mistake via an early `return` statement, so `combineReducers` throws if you do that instead of letting the error manifest itself somewhere else.
 
-* If the `state` given to it is `undefined`, it must return the initial state for this specific reducer. According to the previous rule, the initial state must not be `undefined` either. It is handy to to specify it with ES6 optional arguments syntax, but you can also explicitly check the first argument for being `undefined`.
+* If the `state` given to it is `undefined`, it must return the initial state for this specific reducer. According to the previous rule, the initial state must not be `undefined` either. It is handy to specify it with ES6 optional arguments syntax, but you can also explicitly check the first argument for being `undefined`.
 
 While `combineReducers` attempts to check that your reducers conform to some of these rules, you should remember them, and do your best to follow them.