docs[patch]: added `Templates Hub` menu item (#14148)

This link was missing in Docs.
Added it.

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

docs/docusaurus.config.js

@@ -237,6 +237,10 @@ const config = {
                 href: "https://github.com/langchain-ai/langchain/tree/master/templates",
                 label: "Templates GitHub",
               },
+              {
+                label: "Templates Hub",
+                href: "https://templates.langchain.com",
+              },
               {
                 href: "https://smith.langchain.com/hub",
                 label: "LangChain Hub",