Update index.mdx (#462)

Link to platform directly from this page for folks trying to find the
platform rather than the docs

docs/index.mdx

@@ -27,7 +27,7 @@ import DocCardList from "@theme/DocCardList";
 
 ## Introduction
 
-**LangSmith** is a platform for building production-grade LLM applications. It allows you to closely monitor and evaluate your application, so you can ship quickly and with confidence. Use of LangChain is not necessary - LangSmith works on its own!
+[LangSmith](https://smith.langchain.com/) is a platform for building production-grade LLM applications. It allows you to closely monitor and evaluate your application, so you can ship quickly and with confidence. Use of LangChain is not necessary - LangSmith works on its own!
 
 ## Install LangSmith