[DOC] Update k-NN Lucene Engine Dimension Limit to 16k

[junqiu-lei]

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Tell us about your request. Provide a summary of the request and all versions that are affected.
In v2.12.0, we have updated the k-NN Lucene engine dimension limit from 1,024 to 16,000. The document need to be updated coordinately.

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

• PR: Increase Lucene max dimension limit to 16,000 k-NN#1346
• Document location:
  https://opensearch.org/docs/2.11/search-plugins/knn/approximate-knn#:~:text=The%20knn_vector%20data%20type%20supports%20a%20vector%20of%20floats%20that%20can%20have%20a%20dimension%20count%20of%20up%20to%2016%2C000%20for%20the%20nmslib%20and%20faiss%20engines%2C%20as%20set%20by%20the%20dimension%20mapping%20parameter.%20The%20maximum%20dimension%20count%20for%20the%20Lucene%20library%20is%201%2C024