[Backport 2.12] Add release notes for 2.12.0 release

[ryanbogan]

Description

Backport of #1463

Issues Resolved

[List any issues this PR will resolve]

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed as per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (372a2ae) 84.87% compared to head (a471e0a) 84.95%.

Additional details and impacted files

@@             Coverage Diff              @@
##               2.12    #1466      +/-   ##
============================================
+ Coverage     84.87%   84.95%   +0.07%     
- Complexity     1251     1252       +1     
============================================
  Files           162      162              
  Lines          5131     5131              
  Branches        493      493              
============================================
+ Hits           4355     4359       +4     
+ Misses          567      564       -3     
+ Partials        209      208       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.