add link to the advanced clinical data notebook

Author: fedorov

notebooks/getting_started/exploring_clinical_data.ipynb

@@ -40,6 +40,8 @@
         "\n",
         "If you have never worked with IDC before, we recommend you first complete the getting started tutorial [here](https://github.com/ImagingDataCommons/IDC-Tutorials/blob/master/notebooks/getting_started/part2_searching_basics.ipynb).\n",
         "\n",
+        "For more extensive notebook on exploring clinical data please see [this notebook](https://github.com/ImagingDataCommons/IDC-Tutorials/blob/master/notebooks/advanced_topics/clinical_data_intro.ipynb).\n",
+        "\n",
         "---\n",
         "Initial version: Jul 2024\n",
         "\n",
@@ -1839,4 +1841,4 @@
       }
     }
   ]
-}
+}