Please add v6 (alpha)

[nohwnd]

Checklist

• [X] Issue has a meaningful title
• [X] I have searched the existing issues. See issues

Summary of the request

Pester main was rebranded to 6.0.0-alpha1, if possible, please add copy of docs for v6 (alpha), so we can keep it up to date with the changes.

Keep the v5 shown by default please.

Suggested section

None