fix HOC doc (#8802)

docs/docs/higher-order-components.md

@@ -72,8 +72,8 @@ Later, you write a component for subscribing to a single blog post, which follow
 
 ```js
 class BlogPost extends React.Component {
-  constructor() {
-    super();
+  constructor(props) {
+    super(props);
     this.handleChange = this.handleChange.bind(this);
     this.state = {
       blogPost: DataSource.getBlogPost(props.id)