docs: Added guide to migrate to Ubuntu 24.04

[Xartos]

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What does this PR do / why do we need this PR?

Migration docs for how to migrate to ubuntu 24.04

• Fixes elastisys/ck8s-issue-tracker#348

Information to reviewers

Checklist

• Proper commit message prefix on all commits
• Change checks:
  • The change is transparent
  • The change is disruptive
  • The change requires no migration steps
  • The change requires migration steps
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  • The metrics are still exposed and present in Grafana after the change
  • The metrics names didn't change (Grafana dashboards and Prometheus alerts are not affected)
  • The metrics names did change (Grafana dashboards and Prometheus alerts were fixed)
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[aarnq]

Nice and clear steps 👍

[aarnq]

Please rename this file to 20.04-to-22.04-openstack.md to make it clearer that it is only for openstack.

[Xartos]

064086c

[aarnq]

Yeah, that was an error on my part of course it should be 20.04-to-24.04-openstack.md 😅

[Xartos]

Yea, I should've seen that as well 🙈

[Ajarmar]

Looks great. Minor thing: the document is named 20.04-to-22.04, but it should be 20.04-to-24.04, right?

[Ajarmar]

Could you update these ones as well?

[Ajarmar]

Suggested change

	> This is only needed if you are using DNS and are pointing that to the IPs of the control plane nodes.
	> Updating the DNS records is only needed if you are using DNS and are pointing that to the IPs of the control plane nodes.

[Ajarmar]

Suggested change

	> This is only needed if you are using a loadbalancer in front of the API server.
	> Updating the loadbalancer is only needed if you are using a loadbalancer in front of the API server.

[Ajarmar]

Suggested change

	> This will likely fail at some point in one or two ways:
	> Removing the old control plane nodes will likely fail at some point in one or two ways:

[Ajarmar]

Suggested change

	> This is not needed if you are using a loadbalancer in front of the API server.
	> Removing the old IPs from `supplementary_addresses_in_ssl_keys` is not needed if you are using a loadbalancer in front of the API server.

[Xartos]

Could you update these ones as well?

I thought I searched for This but I've must've misspelled 🙈 I hope I got all now

[viktor-f]

Very nice that we can now do this migration!