Briefly explain static file routing in the getting started guide

guides/source/getting_started.textile

@@ -193,7 +193,7 @@ Now that we have made the controller and view, we need to tell Rails when we wan
 
 To fix this, delete the +index.html+ file located inside the +public+ directory of the application.
 
-You need to do this because Rails will serve any static file in the +public+ directory that matches a route in preference to any dynamic content you generate from the controllers.
+You need to do this because Rails will serve any static file in the +public+ directory that matches a route in preference to any dynamic content you generate from the controllers. The +index.html+ file is special: it will be served if a request comes in at the root route, e.g. http://localhost:3000. If another request such as http://localhost:3000/welcome happened, a static file at <filename>public/welcome.html</filename> would be served first, but only if it existed.
 
 Next, you have to tell Rails where your actual home page is located.