Refresh documentation and blog posts for the package repositories (`pkgs.k8s.io`)

[xmudrii]

We should go through all documents and blog posts mentioning the package repositories to make sure they reflect the current state of the world. There might be several important documents that are out of date. We also talked about refreshing the blog post and potentially publishing a new one that recaps our efforts.

/kind documentation
/sig release
/triage accepted
/priority important-soon

[xmudrii]

We need to make sure we document how to refresh the GPG key once expired/needed: #3840

[k8s-triage-robot]

This issue is labeled with priority/important-soon but has not been updated in over 90 days, and should be re-triaged.
Important-soon issues must be staffed and worked on either currently, or very soon, ideally in time for the next release.

You can:

• Confirm that this issue is still relevant with /triage accepted (org members only)
• Deprioritize it with /priority important-longterm or /priority backlog
• Close this issue with /close

For more details on the triage process, see https://www.kubernetes.dev/docs/guide/issue-triage/

/remove-triage accepted

[xmudrii]

/triage accepted