Add link to the Makie website in the Repo Settings

[logankilpatrick]

Set this as the repo url: https://docs.makie.org/stable/ so that people know for sure what the website this repo is for

[SimonDanisch]

The Makie website isn't really online yet 😅 I just copied a bit from the Makie docs and thought I could quickly make a little website outside the docs, but time run out too quickly.
Now, it just redirects to the docs, but in the future, the content for makie.org should live here.