docs: Updating cookbook README for amazon personalize (#17854)
This PR is a successor to this PR -
https://github.com/langchain-ai/langchain/pull/17436
This PR updates the cookbook README with the notebook so that it is
available on langchain docs for discoverability.
cc: @baskaryan, @3coins
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Co-authored-by: Bagatur <baskaryan@gmail.com>