[Docs] Update K8s documentation according to the latest version Epiphany supports

[atsikham]

Is your feature request related to a problem? Please describe.
After completion some of tasks related to K8s upgrade - #2093, #2658, #2659, #2660 it's necessary to check if K8s documentation we have is up-to-date. This task includes verifying what's changed in those tasks + additional updates.

Describe the solution you'd like
Update documentation.

Describe alternatives you've considered

Additional context

• https://github.com/epiphany-platform/epiphany/blob/develop/docs/home/howto/KUBERNETES.md
• https://github.com/epiphany-platform/epiphany/blob/develop/docs/home/CERTIFICATES.md
• https://github.com/epiphany-platform/epiphany/blob/develop/docs/home/howto/UPGRADE.md
• https://github.com/epiphany-platform/epiphany/blob/develop/docs/home/howto/MAINTENANCE.md
• https://github.com/epiphany-platform/epiphany/blob/develop/docs/home/howto/CLUSTER.md

Search for anything below the current version, eg "epiphany 0.6.0", "1.14", "1.15", etc

---

DoD checklist

• Changelog updated
• COMPONENTS.md updated / doesn't need to be updated
• Schema updated / doesn't need to be updated
• Feature has automated tests
• Automated tests passed (QA pipelines)
  • apply
  • upgrade
• Idempotency tested
• Documentation added / updated / doesn't need to be updated
• All conversations in PR resolved
• Solution meets requirements and is done according to design doc
• Usage compliant with license
• Backport tasks created / doesn't need to be backported