[BUG] Compatibility matrix is missing compatible server versions

[wbeckler]

What is the bug?

There is no mention of server version 2.4 here: https://github.com/opensearch-project/opensearch-java/blob/main/COMPATIBILITY.md

It would also be useful to know whether the client can work with older versions of opensearch or elasticsearch, so people can know if they can upgrade their client before upgrading their server.

[andrross]

It looks like this has gotten more stale...there's no mention of server 2.4 or 2.5, nor is there a mention of client 2.2.0.

[AmiStrn]

This is alarming since I was just about to write an implementation using this client. How is it being tested against the latest versions?

[dblock]

Server is following semver, so I don't expect anything to break. We are running integration tests against a matrix in https://github.com/opensearch-project/opensearch-java/blob/main/.github/workflows/test-integration.yml#L19, let's add 2.4 and update the docs. @AmiStrn if you want to beat me to this PR, go for it! @wbeckler I think we need to schedule this work with every release of OpenSearch so we're not behind.

[AmiStrn]

Timezones... sure @dblock ill make the changes :)

[AmiStrn]

@dblock I made the quick change:) thanks for clearing this up for us. ran the tests locally and nothing broke.