Add doc for neural-sparse-query-two-phase-processor.

[conggguan]

Description

Add the neural sparse two-phase processor document.

Issues Resolved

Resolve 7289.

Version

2.15

Checklist

• By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and subject to the Developers Certificate of Origin.

[zhichao-aws]

Can we give some example API calling like the section ## Setting a default model on an index or field? Using all default values is also good, this would help users a lot

[zhichao-aws]

We should also mention that this processor is strongly recommended to set

[conggguan]

Gave a example API for set a default 2-phase pipeline.
Add a explanation for why we recommend this pipeline.

[zhichao-aws]

fine-tune is usually used for ML models, maybe we should use rescore here

[conggguan]

Replaced with word rescore.

[zhichao-aws]

is this sparse_vector search or end to end latency

[zhichao-aws]

also depending on the index configuration and two-phase parameters Do you mean this depends on the dataset distribution? Because I think we're using default two-phase parameters and consistent index settings in our experiments

[conggguan]

is this sparse_vector search or end to end latency

end to end.

[conggguan]

also depending on the index configuration and two-phase parameters Do you mean this depends on the dataset distribution? Because I think we're using default two-phase parameters and consistent index settings in our experiments

Yes, i corrected the description to index specific data distribution and dataset size .

[zhichao-aws]

end to end.

I think the speed up ratio on pure sparse vector is more important. The model inference cost and retrieval cost is orthogonal and the 2-phase pipeline only optimize the retrieval cost.

[Naarcha-AWS]

@conggguan: Would there be a reason for someone not to create and enable a two-phase processor?

[Naarcha-AWS]

Going to remove this sentence for now.

[natebower]

@Naarcha-AWS @conggguan Please see my comments and changes and tag me for approval when complete. Thanks!

[natebower]

@Naarcha-AWS @conggguan LGTM!