React.createElement syntax (#9459)

* React.createElement syntax

Added React.createElement syntax.
I think this is required for this tutorial.

* Reword

tutorial/tutorial.md

@@ -93,11 +93,13 @@ The `render` method returns a *description* of what you want to render, and then
 
 ```javascript
 return React.createElement('div', {className: 'shopping-list'},
-  React.createElement('h1', ...),
-  React.createElement('ul', ...)
+  React.createElement('h1', /* ... h1 children ... */),
+  React.createElement('ul', /* ... ul children ... */)
 );
 ```
 
+If you're curious, `createElement()` is described in more detail in the [API reference](/react/docs/react-api.html#createelement), but we won't be using it directly in this tutorial. Instead, we will keep using JSX.
+
 You can put any JavaScript expression within braces inside JSX. Each React element is a real JavaScript object that you can store in a variable or pass around your program.
 
 The `ShoppingList` component only renders built-in DOM components, but you can compose custom React components just as easily, by writing `<ShoppingList />`. Each component is encapsulated so it can operate independently, which allows you to build complex UIs out of simple components.