docs: v2.2 updates

[polarweasel]

Release 2.2 docs (Sept 30, 2026):

• Release notes
• Docs updates
• Update release tags (2.0 to EOL, 2.1 to maintenance, 2.2 to current)
• Tag any new deprecations with a Fern
• Update the New badges in this order:
  • Remove New badges from pages that have them
  • Add New badges for what's new in 2.2
• ...

Code of Conduct

• I agree to follow NVIDIA Infra Controller's Code of Conduct
• I have searched the open documentation issues and have found no duplicates for this documentation issue