docs: fix blockchain and mintbase descriptions at https://python.langchain.com/docs/integrations/document_loaders/ All document loaders section (#31369)

…chain.com/docs/integrations/document_loaders/ All document loaders
section

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docs/docs/integrations/document_loaders/blockchain.ipynb

@@ -9,15 +9,6 @@
     "# Blockchain"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "metadata": {
-    "id": "5WjXERXzFEhg"
-   },
-   "source": [
-    "## Overview"
-   ]
-  },
   {
    "attachments": {},
    "cell_type": "markdown",

docs/docs/integrations/document_loaders/mintbase.ipynb

@@ -9,15 +9,6 @@
     "# Near Blockchain"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "metadata": {
-    "id": "5WjXERXzFEhg"
-   },
-   "source": [
-    "## Overview"
-   ]
-  },
   {
    "attachments": {},
    "cell_type": "markdown",