Fix link for MongoDBAtlasVectorSearch in README (#284)

Author: Jibola

README.md

@@ -19,7 +19,7 @@ It contains the following packages.
 - [MongoDBAtlasFullTextSearchRetriever](https://python.langchain.com/docs/integrations/providers/mongodb_atlas/#full-text-search-retriever)
 - [MongoDBAtlasHybridSearchRetriever](https://python.langchain.com/docs/integrations/providers/mongodb_atlas/#hybrid-search-retriever)
 - [MongoDBAtlasSemanticCache](https://python.langchain.com/docs/integrations/providers/mongodb_atlas/#mongodbatlassemanticcache)
-- [MongoDBAtlasVectorSearch](https://python.langchain.com/docs/integrations/vectorstores/mongodb_atlas/)
+- [MongoDBAtlasVectorSearch](https://docs.langchain.com/oss/python/integrations/vectorstores/mongodb_atlas)
 - [MongoDBCache](https://python.langchain.com/docs/integrations/providers/mongodb_atlas/#mongodbcache)
 - [MongoDBChatMessageHistory](https://python.langchain.com/docs/integrations/memory/mongodb_chat_message_history/)