Features
* Add document loader ([9](https://github.com/googleapis/langchain-google-spanner-python/issues/9)) ([7a77d26](https://github.com/googleapis/langchain-google-spanner-python/commit/7a77d2616e2feacd7130852adb6e5d2aaab81da2))
* Spanner Implementation for Vector Store ([10](https://github.com/googleapis/langchain-google-spanner-python/issues/10)) ([9cbae82](https://github.com/googleapis/langchain-google-spanner-python/commit/9cbae82b4c2093344071124b08f1a745a77580a7))
* SpannerChatMessageHistory implementation ([7](https://github.com/googleapis/langchain-google-spanner-python/issues/7)) ([f9a3b93](https://github.com/googleapis/langchain-google-spanner-python/commit/f9a3b931dd61079ddb16f410ab2f9c47bde623ea))
Documentation
* Update README.md ([22](https://github.com/googleapis/langchain-google-spanner-python/issues/22)) ([e9eb86b](https://github.com/googleapis/langchain-google-spanner-python/commit/e9eb86babba490fd0dbb19e67ad50603d5959615))
* Vector store notebook docs ([18](https://github.com/googleapis/langchain-google-spanner-python/issues/18)) ([4c1bd91](https://github.com/googleapis/langchain-google-spanner-python/commit/4c1bd917db03408058dd5169a8047990590cf43b))