Add release notes for 2.12.0 release

[ryanbogan]

Description

Add release notes for 2.12.0 release

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 (1bb48e2) 84.43% compared to head (241adc6) 84.43%.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #593   +/-   ##
=========================================
  Coverage     84.43%   84.43%           
  Complexity      603      603           
=========================================
  Files            48       48           
  Lines          1825     1825           
  Branches        275      275           
=========================================
  Hits           1541     1541           
  Misses          161      161           
  Partials        123      123           

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[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.x 2.x
# Navigate to the new working tree
cd .worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-593-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 d0f8559299f14c784469599bd877d8e9e597e13c
# Push it to GitHub
git push --set-upstream origin backport/backport-593-to-2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-593-to-2.x.

[opensearch-trigger-bot]

The backport to 2.12 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.12 2.12
# Navigate to the new working tree
cd .worktrees/backport-2.12
# Create a new branch
git switch --create backport/backport-593-to-2.12
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 d0f8559299f14c784469599bd877d8e9e597e13c
# Push it to GitHub
git push --set-upstream origin backport/backport-593-to-2.12
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.12

Then, create a pull request where the base branch is 2.12 and the compare/head branch is backport/backport-593-to-2.12.

[ryanbogan]

Will raise manual backports