Add changelog for logs UI refresh (April 1, 2026)

[cloudflare-noelle]

New UI features for Access authentication logs and Gateway activity logs:

• Filter by field
• Customizable fields
• View details by timestamp
• Switch to classic view option

Includes screenshot of the new UI.

Summary

Screenshots (optional)

Documentation checklist

• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.

[cloudflare-noelle]

I attempted to create links based on the new logs docs structure: #29199

So this should be merged after that