docs: The tier label on enterprise pages always links to the "next" version

[makkes]

On enterprise pages such as https://docs.gitops.weave.works/docs/0.8.1/cluster-management/getting-started/ (0.8.1) or https://docs.gitops.weave.works/docs/cluster-management/getting-started/ (current) the little "enterprise" tier label right to the heading always links to the "next" version instead of the one that the user is currently looking at.