Document override_main_response_version

[dblock]

A cluster setting was introduced in opensearch-project/OpenSearch#847. We removed the distribution in backwards-compatible mode in opensearch-project/OpenSearch#898. Set compatibility.override_main_response_version to put the cluster into a configuration that returns 7.10.2 as with ES OSS.

Currently https://docs-beta.opensearch.org/clients/agents-and-ingestion-tools/index/ point to "yes via a cluster setting" which links to opensearch-project/OpenSearch#693, but should be linking to the documentation that explains how to set this setting.

[aetter]

@dblock Is version.number in opensearch.yml still present/required, or is override_main_response_version all a user needs to set? Ordinarily I'd test this sort of thing, but https://hub.docker.com/r/opensearchstaging/opensearch/tags.

[dblock]

@dblock Is version.number in opensearch.yml still present/required, or is override_main_response_version all a user needs to set? Ordinarily I'd test this sort of thing, but https://hub.docker.com/r/opensearchstaging/opensearch/tags.

@mch2 can provide all the details as needed

[mch2]

@aetter compatibility.override_main_response_version is all a user needs to set. This can be enabled via opensearch.yml or toggled as a cluster setting:

PUT /_cluster/settings
{
  "compatibility" : {
    "override_main_response_version" : true
  }
}

[dblock]

Closed via #77