Add Notebooks to Docs/Sphinx (#1039)

...ples/chatgpt_plugin/ChatGPT_Retrieval_Plugin_Upload.ipynb

examples/composable_indices/QASummaryGraph.ipynb

examples/cost_analysis/TokenPredictor.ipynb

examples/data_connectors/DatabaseReaderDemo.ipynb

examples/data_connectors/GithubRepositoryReaderDemo.ipynb

examples/data_connectors/MboxReaderDemo.ipynb

examples/data_connectors/ObsidianReaderDemo.ipynb

examples/data_connectors/TwitterDemo.ipynb

examples/data_connectors/WeaviateDemo.ipynb

examples/evaluation/GuardrailsDemo.ipynb

examples/evaluation/LangchainOutputParserDemo.ipynb

examples/evaluation/TestNYC-Evaluation.ipynb

examples/gatsby/TestGatsby.ipynb

examples/knowledge_graph/KnowledgeGraphDemo.ipynb

examples/langchain_demo/LangchainDemo.ipynb

examples/multimodal/Multimodal.ipynb

examples/optimizer/OptimizerDemo.ipynb

examples/paul_graham_essay/DavinciComparison.ipynb

examples/paul_graham_essay/GPT4Comparison.ipynb

examples/paul_graham_essay/InsertDemo.ipynb