[FEATURE] How to signal a release is no longer supported?

Is your feature request related to a problem? Please describe.
OpenSearch has a support policy to indicating that the latest Minor Patch version for a Major version are supported and will see future releases. As of this writing 1.3.5 and 2.3.0 are supported and 3.0.0 is is under active development.

However, there are many branches in the codebase and the plugin codebases that are not supported - as in they will never be releases as part of an OpenSearch distribution. Branches like this include OpenSearch's 1.0, 1.1 releases and there are some plugins with opendistro-* branches.

Describe the solution you'd like
It should be easy for members and contributors of OpenSearch-project to know what branches are supported and if a branch is no longer supported.

Describe alternatives you've considered

• There could be a gadget on github repositories that shows the current in-progress version.
• Branches could be deleted after tags have been created.
• Branches could be cleaned of repository content with a pointer to "go here for latest supported versions"

Additional context
From https://github.com/opensearch-project/security/pull/2009#issuecomment-1213432982 there was a set of 5 pull requests to backport a changes so it could be consumed by a private fork. These changes depended on legacy build and test systems that are virtual non-functional. Rather than accepting merges for changes that 'might' work with failing CI, it seems more appropriate to guide contributors away from such courses of action

Start by reviewing this issue in the opensearch-project/.github repository and the referenced security pull request comment. Compare the proposed approaches for identifying supported branches across OpenSearch and plugin repositories. Done should make supported and unsupported branches easy for contributors to distinguish, but the issue does not specify which approach or files to change.