[chore] Add links to releases for k8s migration guide breaking changes

[ChrsMark]

The k8s migration guide should link to specific SemConv releases (once those are available) for any introduced breaking changes. This PR fixes the already existing ones.

I could not come up with sth more elegant that'd automate this work but if @open-telemetry/specs-semconv-approvers have any ideas I'd love to know. Otherwise I will keep an eye for keeping them up to date manually 🙂.

Ref to the respective release: https://github.com/open-telemetry/semantic-conventions/releases/tag/v1.30.0

Merge requirement checklist

• [x] CONTRIBUTING.md guidelines followed.
• [ ] Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• [ ] schema-next.yaml updated with changes to existing conventions.