docs: reorg and visual refresh (#19765)

- put use cases in main sidebar
- move modules to own sidebar, rename components
- cleanup lcel section
- cleanup guides
- update font, cell highlighting

---------

Co-authored-by: Chester Curme <chester.curme@gmail.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

cookbook/LLaMA2_sql_chat.ipynb

@@ -38,9 +38,9 @@
     "\n",
     "To run locally, we use Ollama.ai. \n",
     "\n",
-    "See [here](https://python.langchain.com/docs/integrations/chat/ollama) for details on installation and setup.\n",
+    "See [here](/docs/integrations/chat/ollama) for details on installation and setup.\n",
     "\n",
-    "Also, see [here](https://python.langchain.com/docs/guides/local_llms) for our full guide on local LLMs.\n",
+    "Also, see [here](/docs/guides/development/local_llms) for our full guide on local LLMs.\n",
     " \n",
     "To use an external API, which is not private, we can use Replicate."
    ]

cookbook/Semi_structured_multi_modal_RAG_LLaMA2.ipynb

@@ -191,15 +191,15 @@
    "source": [
     "## Multi-vector retriever\n",
     "\n",
-    "Use [multi-vector-retriever](https://python.langchain.com/docs/modules/data_connection/retrievers/multi_vector#summary).\n",
+    "Use [multi-vector-retriever](/docs/modules/data_connection/retrievers/multi_vector#summary).\n",
     "\n",
     "Summaries are used to retrieve raw tables and / or raw chunks of text.\n",
     "\n",
     "### Text and Table summaries\n",
     "\n",
-    "Here, we use ollama.ai to run LLaMA2 locally. \n",
+    "Here, we use Ollama to run LLaMA2 locally. \n",
     "\n",
-    "See details on installation [here](https://python.langchain.com/docs/guides/local_llms)."
+    "See details on installation [here](/docs/guides/development/local_llms)."
    ]
   },
   {