docs: fix vectara description at https://python.langchain.com/docs/integrations/chat/ All chat models section (#31316)

…tegrations/chat/ All chat models section

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docs/docs/integrations/chat/vectara.ipynb

@@ -5,8 +5,6 @@
    "id": "134a0785",
    "metadata": {},
    "source": [
-    "## Overview\n",
-    "\n",
     "[Vectara](https://vectara.com/) is the trusted AI Assistant and Agent platform which focuses on enterprise readiness for mission-critical applications.\n",
     "Vectara serverless RAG-as-a-service provides all the components of RAG behind an easy-to-use API, including:\n",
     "1. A way to extract text from files (PDF, PPT, DOCX, etc)\n",