[DOC] Faiss Engine Efficient Filtering

[navneet1v]

What do you want to do?

• Request a change to existing documentation
• Add new documentation

Tell us about your request. Provide a summary of the request and all versions that are affected.
As of OpenSearch 2.8 version, pre-filtering/Efficient Filtering was only support with Lucene engine in K-NN plugin. With this feature: , we K-NN plugin will start to support the pre-filtering/Efficient Filtering for Faiss Engine too. As of now, we are planning to release this feature in v2.9.

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.
opensearch-project/k-NN#903