[AUTO] Add release notes for 3.2.0

[opensearch-ci-bot]

Add release notes for 3.2.0

[gaiksaya]

Hi maintainers,

This is the first time we are trying the automation to create release notes based on the changes/commits that went in since last release (3.1.0) which was on June 24, 2025.
Please review the PR and provide feedback. Please feel free to commit the changes in the PR branch.
More details on the workflow
cc: @rishabh6788

[amitgalitz]

Lots of PRs are missing

[rishabh6788]

It is so because the repo has a CHANGELOG.md file that has not been updated for the commits that have been merged, and the workflow first checks for changelog and if it doesn't exist it then goes through list of commits.
If you have a CHANEGLOG.md please make sure it is up to date with latest commits else please remove it. @amitgalitz

[amitgalitz]

Didn't realize we added CHANGELOG.md to this repo, its not been used except one PR. we always relay on this: https://github.com/opensearch-project/anomaly-detection/blob/main/.github/workflows/draft-release-notes-workflow.yml

[amitgalitz]

I'll update changelog

[gaiksaya]

Closing in favor of https://github.com/opensearch-project/anomaly-detection-dashboards-plugin/pull/1074/files