[DOC] Add support for Bedrock Rerank API

[tkykenmt]

What do you want to do?

• Request a change to existing documentation
• Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request.
Amazon Bedrock introduced Rerank model support. Since 2.19, OpenSearch will be able to invoke Rerank models on Amazon Bedrock with no implementation on custom pre and post functions using pre-built functions. I've created original issue [1] and PR [2].

I'd like to submit tutorial on reranking using Bedrock Rerank API.

Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.
2.19-

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

[1] opensearch-project/ml-commons#3254
[2] opensearch-project/ml-commons#3339