Fix links in the README.md

Author: MangelMaxime

README.md

@@ -4,5 +4,5 @@ This library aims to provide you a nice way to inform the user that something oc
 
 It also provides a very basic input system. Do not abuse it, a toast should be about notifying the user, not asking them to perform an action.
 
-- Documentation available [here](https://thoth-org.github.io/Thoth.Elmish.Toast/)
-- Demo available [here](https://thoth-org.github.io/Thoth.Elmish.Toast/demo.html)
+- Documentation available [here](https://thoth-org.gitbook.io/thoth-elmish-toast/)
+- Demo available [here](https://thoth-org.github.io/Thoth.Elmish.Toast/)