Separate v2 docs

[keithamus]

It's getting a little difficult to manage the v2 branch documentation, and as we migrate to v2 and more projects use it, it is becoming more useful to consult the v2 docs on the live site.

As such, this adds a v2 version of the documentation, which gives us the opportunity to view the two docs on the site.

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[koddsson]

Looks good to me!