"Introducing JSX" is missing a step (#812)

* Introducing JSX is missing a step

* Tweak

Author: stmoreau

content/docs/introducing-jsx.md

@@ -30,9 +30,21 @@ With that out of the way, let's get started!
 
 ### Embedding Expressions in JSX
 
-You can embed any [JavaScript expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Expressions) in JSX by wrapping it in curly braces.
+In the example below, we declare a variable called `name` and then use it inside JSX by wrapping it in curly braces:
 
-For example, `2 + 2`, `user.firstName`, and `formatName(user)` are all valid expressions:
+```js{1,2}
+const name = 'Josh Perez';
+const element = <h1>Hello, {name}</h1>;
+
+ReactDOM.render(
+  element,
+  document.getElementById('root')
+);
+```
+
+You can put any valid [JavaScript expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Expressions) inside the curly braces in JSX. For example, `2 + 2`, `user.firstName`, or `formatName(user)` are all valid JavaScript expressions.
+
+In the example below, we embed the result of calling a JavaScript function, `formatName(user)`, into an `<h1>` element.
 
 ```js{12}
 function formatName(user) {