updated readme

Author: Dabit

README.md

@@ -89,10 +89,16 @@ const [data, setString] = useClipboard()
 
 ### `useDimensions`
 
+Gets dimensions and sets up a listener that will change the dimensions if the user changes device orientation.
+
 ```js
 import { useDimensions } from 'react-native-hooks'
 
 const dimensions = useDimensions()
+// or
+const { width, height } = useDimensions().window
+// or
+const screen = useDimensions().screen
 ```
 
 ### `useKeyboard`

lib/useBackHandler.js

@@ -1,7 +1,6 @@
 import React, { useEffect, useState } from 'react'
 import { BackHandler } from 'react-native'
 
-
 export default (handler) => {
   useEffect(() => {
     BackHandler.addEventListener('hardwareBackPress', handler)