DM-54844: Add v30 release notes

[timj]

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.41%. Comparing base (a86675a) to head (8fe5f22).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #133   +/-   ##
=======================================
  Coverage   87.41%   87.41%           
=======================================
  Files          47       47           
  Lines        3887     3887           
=======================================
  Hits         3398     3398           
  Misses        489      489           

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