Unable to view V4 documentation

[JoelHobson]

Describe the bug
The URL for the v4 docs redirects to the v3 docs page.

To Reproduce
Steps to reproduce the behavior:

1. Navigate to https://v4.apollo.vuejs.org/ - it immediately redirects to https://apollo.vuejs.org/ which appears to still be the v3 docs.

Expected behavior
It should take me to the v4 docs.

It looks like I can view the current docs as .md files in this repo so this isn't hugely important, but it would be nice to have them working on the website.