[Vectorize] Fix langchain url (#17188)

* Update langchain.mdx

* Update src/content/docs/vectorize/examples/langchain.mdx

---------

Co-authored-by: Kian <[email protected]>

Author: 2 people

src/content/docs/vectorize/examples/langchain.mdx

@@ -1,7 +1,7 @@
 ---
 pcx_content_type: navigation
 title: LangChain Integration
-external_link: https://js.langchain.com/docs/modules/data_connection/vectorstores/integrations/cloudflare_vectorize
+external_link: https://js.langchain.com/docs/integrations/vectorstores/cloudflare_vectorize/
 sidebar:
   order: 2