docs: add missing install for langchain_community module in tutorials intro (#814)

Co-authored-by: William FH <13333726+hinthornw@users.noreply.github.com>

examples/introduction.ipynb

@@ -410,7 +410,8 @@
    "outputs": [],
    "source": [
     "%%capture --no-stderr\n",
-    "%pip install -U tavily-python"
+    "%pip install -U tavily-python\n",
+    "%pip install -U langchain_community"
    ]
   },
   {