[DOC] Add more details for post filters support to existing Hybrid Query page

[martin-gaievski]

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Tell us about your request. Provide a summary of the request.
Hybrid query today supports post filter with syntax format that is similar to other queries. Unlike with other queries, filters in hybrid query may also affect final scores. We need to state that to minimize customer's confusion, preferably with some example.

This is the section in Hybrid Query page that describes how to use post filters:
https://opensearch.org/docs/latest/search-plugins/hybrid-search/#hybrid-search-with-post-filtering

This is the example we can use:

example 1
assume without filter following documents matches your queries in hybrid query.
query: [ d2: 5.0, d4: 3.0, d1: 2.0 ]
normalized scores [d2: 1.0, d4: 0.33, d1: 0.0]

example 2, with a filter
same query: [ d2: 5.0, d4: 3.0, d1: 2.0 ]
filter matches only [ d2, d4 ]
after the post filter applied this became
[ d2: 1.0, d4: 0.0 ]
you can see that for d4 score changes from 0.33 in example 1 to 0.0

example 3, two sub-queries
query1: [ d2: 5.0, d4: 3.0, d1: 2.0 ], query2: [ d1: 1.0, d5: 0.5, d4: 0.25 ]
normalized scores: [d2: 1.0, d4: 0.33, d1: 0.0], [d1: 1.0, d5: 0.33, d4: 0.0]
combined scores: [d2: 1.0, d1: 0.5, d5: 0.33, d4: 0.165]

apply same filter to that results: filter matches [ d2, d4 ]
score became query1: [ d2: 5.0, d4: 3.0], query2: [ d4: 0.25 ]
normalized scores: [ d2: 1.0, d4: 0.0], query2: [ d4: 1.0 ]
combined scores: [d2: 1.0, d4: 0.5]

for d2 score remains the same with and without the filter, but for d4 score has changed

Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.
This applies to all versions where hybrid query supports post filters, starting from 2.13

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