Fix path to main.rs in example after refactoring

Author: mre

README.md

@@ -9,7 +9,7 @@ Wundergraph provides a platform to easily expose your database through a GraphQL
 
 
 ## Example
-For a full example application see the [example project](https://github.com/weiznich/wundergraph/tree/master/wundergraph_example/src/main.rs)
+For a full example application see the [example project](https://github.com/weiznich/wundergraph/blob/master/wundergraph_example/src/bin/main.rs)
 
 ```rust
 #[macro_use] extern crate diesel;