Update recipe index in README

Author: RajeshThallam

genai-on-vertex-ai/gemini/model_upgrades/README.md

@@ -17,4 +17,5 @@ The goal is to accelerate the process of upgrading to the latest version of Gemi
 | Document QnA | [view](./document_qna/vertex_colab/document_qna_eval.ipynb) | [view](./document_qna/vertex_script/README.md) | [view](./document_qna/promptfoo/README.md) |
 | Summarization | [view](./summarization/vertex_colab/summarization_eval.ipynb) | [view](./summarization/vertex_script/README.md) | [view](./summarization/promptfoo/README.md) |
 | Text Classification | [view](./text_classification/vertex_colab/text_classification_eval.ipynb) | [view](./text_classification/vertex_script/README.md) | [view](./text_classification/promptfoo/README.md) |
+| Multi-turn chat | [view](./multiturn_chat/vertex_colab/multiturn_chat_eval.ipynb) | [view](./multiturn_chat/vertex_script/README.md) | [view](./multiturn_chat/promptfoo/README.md) |