Replace CHANGELOG.md with release-notes/AGENTS.md

Use an AI agent steering file to generate release notes from commit
messages, PR descriptions, and PR labels.

Signed-off-by: Andrew Ross <andrross@amazon.com>

Author: andrross

.gitattributes

@@ -12,4 +12,3 @@
 *.p12 binary
 *.ttf binary
 *.txt text=auto
-CHANGELOG.md merge=union

CHANGELOG.md

@@ -6,7 +6,6 @@
     - [Documentation Changes](#documentation-changes)
     - [Contributing Code](#contributing-code)
 - [Developer Certificate of Origin](#developer-certificate-of-origin)
-- [Changelog](#changelog)
 - [Review Process](#review-process)
     - [Tips for Success](#tips)
 - [Troubleshooting Failing Builds](#troubleshooting-failing-builds)
@@ -119,33 +118,6 @@ Signed-off-by: Jane Smith <jane.smith@email.com>
 ```
 You may type this line on your own when writing your commit messages. However, if your user.name and user.email are set in your git configs, you can use `-s` or `--signoff` to add the `Signed-off-by` line to the end of the commit message.
 
-## Changelog
-
-OpenSearch maintains version specific changelog by enforcing a change to the ongoing [CHANGELOG](CHANGELOG.md) file adhering to the [Keep A Changelog](https://keepachangelog.com/en/1.0.0/) format. The purpose of the changelog is for the contributors and maintainers to incrementally build the release notes throughout the development process to avoid a painful and error-prone process of attempting to compile the release notes at release time. On each release the "unreleased" entries of the changelog are moved to the appropriate release notes document in the `./release-notes` folder. Also, incrementally building the changelog provides a concise, human-readable list of significant features that have been added to the unreleased version under development.
-
-### Which changes require a CHANGELOG entry?
-Changelogs are intended for operators/administrators, developers integrating with libraries and APIs, and end-users interacting with OpenSearch Dashboards and/or the REST API (collectively referred to as "user"). In short, any change that a user of OpenSearch might want to be aware of should be included in the changelog. The changelog is _not_ intended to replace the git commit log that developers of OpenSearch itself rely upon. The following are some examples of changes that should be in the changelog:
-
-- A newly added feature
-- A fix for a user-facing bug
-- Dependency updates
-- Fixes for security issues
-
-The following are some examples where a changelog entry is not necessary:
-
-- Adding, modifying, or fixing tests
-- An incremental PR for a larger feature (such features should include _one_ changelog entry for the feature)
-- Documentation changes or code refactoring
-- Build-related changes
-
-Any PR that does not include a changelog entry will result in a failure of the validation workflow in GitHub. If the contributor and maintainers agree that no changelog entry is required, then the `skip-changelog` label can be applied to the PR which will result in the workflow passing.
-
-### How to add my changes to [CHANGELOG](CHANGELOG.md)?
-
-Adding in the change is two step process:
-1. Add your changes to the corresponding section within the CHANGELOG file with dummy pull request information, publish the PR
-2. Update the entry for your change in [`CHANGELOG.md`](CHANGELOG.md) and make sure that you reference the pull request there.
-
 ## Review Process
 
 We deeply appreciate everyone who takes the time to make a contribution. We will review all contributions as quickly as possible. As a reminder, [opening an issue](https://github.com/opensearch-project/OpenSearch/issues/new/choose) discussing your change before you make it is the best way to smooth the PR process. This will prevent a rejection because someone else is already working on the problem, or because the solution is incompatible with the architectural direction.

CONTRIBUTING.md

@@ -1,3 +1,7 @@
 ## Releasing
 
 This project follows [OpenSearch project branching, labelling, and releasing](https://github.com/opensearch-project/.github/blob/main/RELEASING.md).
+
+### Release Notes
+
+The [release notes AGENTS.md file](release-notes/AGENTS.md) is intended to be given to an AI agent as a prompt. It will generate release notes and create a pull request. The agent will need to access commit information from the local git repository as well as permissions to read pull request descriptions and create a new pull request in GitHub.