Use syntax highlighted code block in README.md

GitHub just implemented that and we should use it.
https://github.com/blog/832-rolling-out-the-redcarpet

README.md

@@ -54,6 +54,7 @@ listener a unique name.
 
 Code speaks more than words:
 
+``` erlang
 application:start(cowboy),
 Dispatch = [
     %% {Host, list({Path, Handler, Opts})}
@@ -64,11 +65,13 @@ Code speaks more than words:
     cowboy_tcp_transport, [{port, 8080}],
     cowboy_http_protocol, [{dispatch, Dispatch}]
 ).
+```
 
 You must also write the `my_handler` module to process requests. You can
 use one of the predefined handlers or write your own. An hello world HTTP
 handler could be written like this:
 
+``` erlang
 -module(my_handler).
 -export([init/3, handle/2, terminate/2]).
 
@@ -81,3 +84,4 @@ handler could be written like this:
 
 terminate(Req, State) ->
     ok.
+```