RAG: Question Answering using Gemma, Elasticsearch & langchain

This is Ashish from [Elastic](https://www.elastic.co/). I'm interested in sharing a notebook that showcases RAG implementation using Elasticsearch. The notebook will illustrate how we generate vectors using Elastic's ELSER model and retrieve semantic results. We'll be utilizing Gemma for contextual question answering.

Review the cookbook's existing notebook structure and identify where a RAG example using Elasticsearch, ELSER, and Gemma would fit. Confirm the expected setup and presentation conventions before adding the notebook. Done means a self-contained notebook demonstrates vector generation, semantic retrieval, and contextual question answering.

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