Updated learning the code (markdown)

learning-the-code.md

@@ -19,7 +19,7 @@ Under `client/pages/` you'll find `app.jsx`, which is the main switchboard for t
 
 The routes have two different ways of loading a page:
 
-```js
+```jsx
 <LazyRoute path='/login' component={() => import('./accounts/login')} />
 
 <LazyRoute path='/credits' component={async () => () => <MarkdownPage content={require('../markdown/credits.md').default} />} />