Merge pull request #179 from mtutty/add-pgvector-store

apps/mongodb/2_load_and_index.ts

apps/mongodb/3_query.ts

apps/simple/mongo.ts

apps/simple/pg-vector-store/README.md

apps/simple/pg-vector-store/load-docs.ts

apps/simple/pg-vector-store/query.ts

examples/clip.ts

examples/mongo.ts

packages/core/package.json

packages/core/src/QueryEngine.ts

packages/core/src/ServiceContext.ts

packages/core/src/embeddings/OpenAIEmbedding.ts

packages/core/src/index.ts

packages/core/src/indices/summary/SummaryIndex.ts

packages/core/src/llm/LLM.ts

packages/core/src/readers/DocxReader.ts

packages/core/src/storage/index.ts

packages/core/src/storage/vectorStore/PGVectorStore.ts

packages/core/src/storage/vectorStore/SimpleVectorStore.ts

packages/core/src/storage/vectorStore/utils.ts