[DOC] Clarify that Snapshot Info (Snashot/Restore APIs) may not return `state` property

[reta]

What do you want to do?

• [X] Request a change to existing documentation
• [ ] Add new documentation
• [ ] Report a technical problem with the documentation
• [ ] Other

Tell us about your request. Provide a summary of the request and all versions that are affected.

The Snapshot APIs may not return state property if snapshot state is unknown or cannot be determined, the example below is taken from one of the production systems:

{
    data_streams: [], 
    include_global_state: True, 
    indices: ["<redacted>"], 
    snapshot: "<redacted>", 
    start_time: '2023-12-06T04:17:10.958Z', 
    start_time_in_millis: 1701836230958
}

The server side and client side models clearly indicate that but sadly not the documentation, that causes confusion. Relevant part of the documentation: https://opensearch.org/docs/latest/tuning-your-cluster/availability-and-recovery/snapshots/snapshot-restore/#take-snapshots

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.

[willyborankin]

@reta it looks like a bug to me. Not missing information in docs.

[reta]

@reta it looks like a bug to me. Not missing information in docs.

@willyborankin Why is that? The API responses for server have it as optional field.

[hdhalter]

@prudhvigodithi - Do you know who might be able to comment on this?