remove extension function in combineReducers. Update comments

lib/src/commonMain/kotlin/org/reduxkotlin/CombineReducers.kt

@@ -0,0 +1,13 @@
+package org.reduxkotlin
+
+fun combineReducers(vararg reducers: Reducer): Reducer =
+    { state, action ->
+        reducers.fold(state, { s, reducer -> reducer(s, action) })
+    }
+
+/**
+ * combine two reducer with + operator
+ */
+operator fun Reducer.plus(other: Reducer): Reducer = { s, a ->
+    other(this(s, a), a)
+}

lib/src/commonMain/kotlin/org/reduxkotlin/Compose.kt

@@ -1,5 +1,8 @@
 package org.reduxkotlin
 
+/**
+ * Composes a list of single argument functions from right to left.
+ */
 fun <T> compose(functions: List<(T) -> T>): (T) -> T =
         { x -> functions.foldRight(x, { f, composed -> f(composed) })
 }

lib/src/commonMain/kotlin/org/reduxkotlin/Definitions.kt

@@ -12,7 +12,7 @@ typealias StoreSubscription = () -> Unit
 typealias Dispatcher = (Any) -> Any
 typealias StoreCreator = (reducer: Reducer, initialState: Any, s: StoreEnhancerWrapper?) -> Store
 /**
- * get a store creator and return a new enhanced one
+ * Take a store creator and return a new enhanced one
  * see https://github.com/reactjs/redux/blob/master/docs/Glossary.md#store-enhancer
  */
 typealias StoreEnhancer = (next: StoreCreator) -> StoreCreator
@@ -28,7 +28,7 @@ class StoreEnhancerWrapper(val storeEnhancer2: StoreEnhancer) : StoreEnhancer {
 }
 
 /**
- * see also https://github.com/reactjs/redux/blob/master/docs/Glossary.md#middleware
+ *  https://github.com/reactjs/redux/blob/master/docs/Glossary.md#middleware
  */
 typealias Middleware = (store: Store) -> (next: Dispatcher) -> (action: Any) -> Any