re-bold some text so it stands out better

docs/02-displaying-data.md

@@ -80,7 +80,7 @@ React components are very simple. You can think of them as simple function that
 
 We strongly believe that components are the right way to separate concerns rather than "templates" and "display logic." We think that markup and the code that generates it are intimately tied together. Additionally, display logic is often very complex and using template languages to express it becomes cumbersome.
 
-We've found that the best solution for this problem is to generate markup directly from the JavaScript code such that you can use all of the expressive power of a real programming language to build UIs. In order to make this easier, we've added a very simple, *optional* HTML-like syntax for the function calls that generate markup called JSX.
+We've found that the best solution for this problem is to generate markup directly from the JavaScript code such that you can use all of the expressive power of a real programming language to build UIs. In order to make this easier, we've added a very simple, **optional** HTML-like syntax for the function calls that generate markup called JSX.
 
 **JSX lets you write JavaScript function calls with HTML syntax.** To generate a link in React using pure JavaScript you'd write: `React.DOM.a({href: 'http://facebook.github.io/react/'}, 'Hello React!')`. With JSX this becomes `<a href="http://facebook.github.io/react/">Hello React!</a>`. We've found this has made building React apps easier and designers tend to prefer the syntax, but everyone has their own workflow, so **JSX is not required to use React.**