Update README.md

fix website address

README.md

@@ -98,7 +98,7 @@ These files are used by the [UnoGrasp code](https://github.com/tev-fbk/UnoGrasp/
 
 ### Challenge Files
 
-These files are used by the [UnoBench Challenge](https://unochallenge.nnrex.org/).
+These files are used by the [UnoBench Challenge](https://unobenchchallenge.fbk.eu/).
 
 | File | Description |
 | --- | --- |