Fix URL formatting

Author: joestephens

README.md

@@ -13,7 +13,7 @@ npm install
 npm start
 ```
 
-Visit [http://localhost:3000/] in your browser and you should see `Hello world!`. You can dive in and start coding your own routes in `src/app.js`.
+Visit [http://localhost:3000/](http://localhost:3000/) in your browser and you should see `Hello world!`. You can dive in and start coding your own routes in `src/app.js`.
 
 ## Copy over your JavaScript Basics code