Update references to Twig website

By the looks you dont need to download any extra deps for >=D8, as Twig is already a part of Drupal.

Re-scoping issue to update URL

Ok, But this step i can't find: Go to admin/structure/twig/add and create a template or two

It shows the page 404 can't find.

In addition, it has to do with this module ( filter_twig → ) has a significant difference between them.

The project docs look to relate to the D7 version only. You can see there is no such code in the D8 branches.