docs: `youtube_search` tool example update (#9958)

Added a link to source package; updated title, description.

docs/extras/integrations/tools/youtube.ipynb

@@ -5,9 +5,13 @@
    "id": "acb64858",
    "metadata": {},
    "source": [
-    "# YouTube (youtube_search)\n",
+    "# YouTube\n",
     "\n",
-    "This notebook shows how to use a tool to search `YouTube` using `youtube_search` package.\n",
+    ">[YouTube Search](https://github.com/joetats/youtube_search) package searches `YouTube` videos avoiding using their heavily rate-limited API.\n",
+    ">\n",
+    ">It uses the form on the `YouTube` homepage and scrapes the resulting page.\n",
+    "\n",
+    "This notebook shows how to use a tool to search YouTube.\n",
     "\n",
     "Adapted from [https://github.com/venuv/langchain_yt_tools](https://github.com/venuv/langchain_yt_tools)"
    ]