Update the similarity algorithm details

[prudhvigodithi]

Description

Update the similarity algorithm details

Issues Resolved

Closed #9643
Related OpenSearch issue: opensearch-project/OpenSearch#17315

Version

3.0.0

Checklist

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[prudhvigodithi]

Adding @msfroh @getsaurabh02 to the PR.
Thanks

[msfroh]

I would highlight the difference.

Lucene recognized that scores were being multiplied by a constant factor and dropped it.

In OpenSearch 3.0, by default, all scores will be lower by a factor of 2.2 (if I remember correctly). It doesn't affect the order of results, unless you do something that depends on the specific values.

Examples include the min_score query that discards everything below a given score. It may also have implications for hybrid scoring (though I believe that's usually relative to the max score, so the relative scaling should be consistent).