Release notes updates for 4.20

[didoo]

📌 Summary

This is a follow-up of #2864 where we decided to test decoupling the merge of the Version Package PR from the actual update of the release notes (to avoid getting continuously reverted the changes already committed, every time a PR is merged to main).

Previews:

• release notes: https://hds-website-git-420-release-notes-hashicorp.vercel.app/whats-new/release-notes
• component version history (example): https://hds-website-git-420-release-notes-hashicorp.vercel.app/components/code-block?tab=version%20history#4200

🔗 External links

Jira ticket: https://hashicorp.atlassian.net/browse/HDS-4920

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👀 Component checklist

💬 Please consider using conventional comments when reviewing this PR.

📋 PCI review checklist

• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.
• If applicable, I've worked with GRC to document the impact of any changes to security controls.
  Examples of changes to controls include access controls, encryption, logging, etc.
• If applicable, I've worked with GRC to ensure compliance due to a significant change to the in-scope PCI environment.
  Examples include changes to operating systems, ports, protocols, services, cryptography-related components, PII processing code, etc.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
hds-showcase	✅ Ready (Inspect)	Visit Preview	Jun 5, 2025 2:43pm
hds-website	✅ Ready (Inspect)	Visit Preview	Jun 5, 2025 2:43pm

[dchyun]

Only thing I notice is the layout components seem to be missing their updated badges, but that's not an issue with the changes made here and can be fixed later.