docs[patch]: top menu (#13748)

Addressed this issue with the top menu: It allocates too much space. If the screen is small, then the top menu items are split into two lines and look unreadable.
Another issue is with several top menu items: "Chat our docs" and "Also by LangChain". They are compound of several words which also hurts readability. The top menu items should be 1-word size.
Updates:
- "Chat our docs" -> "Chat" (the meaning is clean after clicking/opening the item)
- "Also by LangChain" -> "🦜️🔗"
- "🦜️🔗" moved before "Chat" item. This new item is partially copied from the first left item, the "🦜️🔗 LangChain". This design (with two 🦜️🔗 elements, visually splits the top menu into two parts. The first item in each part holds the 🦜️🔗 symbols and, when we click the second 🦜️🔗 item, it opens the drop-down menu. So, we've got two visually similar parts, which visually split the top menu on the right side: the LangChain Docs (and Doc-related items) and the lift side: other LangChain.ai (company) products/docs.

docs/docusaurus.config.js

@@ -211,14 +211,9 @@ const config = {
               { label: "Gallery", href: "https://github.com/kyrolabs/awesome-langchain" }
             ]
           },
-          {
-            href: "https://chat.langchain.com",
-            label: "Chat our docs",
-            position: "right",
-          },
           {
             type: "dropdown",
-            label: "Also by LangChain",
+            label: "🦜️🔗",
             position: "right",
             items: [
               {
@@ -243,6 +238,11 @@ const config = {
               },
             ]
           },
+          {
+            href: "https://chat.langchain.com",
+            label: "Chat",
+            position: "right",
+          },
           // Please keep GitHub link to the right for consistency.
           {
             href: "https://github.com/langchain-ai/langchain",