Update README on PropType

Author: BookOfGreg

README.md

@@ -90,7 +90,7 @@ Then restart your development server.
 
 This will:
 
-- add some `//= require`s to `application.js`  
+- add some `//= require`s to `application.js`
 - add a `components/` directory for React components
 - add `server_rendering.js` for [server-side rendering](#server-side-rendering)
 
@@ -108,7 +108,7 @@ window.Post = React.createClass({
 // or, equivalent:
 class Post extends React.Component {
   render() {
-    return <h1>{this.props.title}</h1>    
+    return <h1>{this.props.title}</h1>
   }
 }
 ```
@@ -395,11 +395,11 @@ rails g react:component Post title:string published:bool published_by:instanceOf
 would generate:
 
 ```js
-var Post = React.createClass({
+var Post = createReactClass({
   propTypes: {
-    title: React.PropTypes.string,
-    published: React.PropTypes.bool,
-    publishedBy: React.PropTypes.instanceOf(Person)
+    title: PropTypes.string,
+    published: PropTypes.bool,
+    publishedBy: PropTypes.instanceOf(Person)
   },
 
   render: function() {