add NLST clinical data tutorial to the readme

Author: fedorov

README.md

@@ -47,6 +47,7 @@ This folders contains notebooks that demonstrate the usage of the data in the sp
 * [Visible Human Project exploration](https://github.com/ImagingDataCommons/IDC-Tutorials/blob/master/notebooks/collections_demos/nlm_visible_human_project.ipynb): demonstration of searching and visualizing images from the National Library of Medicine Visible Human Project available on IDC.
 * [RMS-Mutation-Prediction collection exploration](https://github.com/ImagingDataCommons/IDC-Tutorials/tree/master/notebooks/collections_demos/rms_mutation_prediction): notebooks in this folder demonstrate selecting images from the `RMS-Mutation-Prediction` collection based on various attributes of images and expert annotations.
 * [NLST collection exploration](https://github.com/ImagingDataCommons/IDC-Tutorials/blob/master/notebooks/collections_demos/nlst_exploration.ipynb): explanation of the content included in the IDC NLST collection, and how it is different from the NLST collection you will find in TCIA.
+* [Working with NLST clinical data in IDC](https://github.com/ImagingDataCommons/IDC-Tutorials/blob/master/notebooks/collections_demos/nlst_clinical_data.ipynb): demonstration of how to access and search clinical data tables accompanying the IDC NLST collection, and how to combine clinical data with imaging metadata.
 
 ## [`pathomics`](https://github.com/ImagingDataCommons/IDC-Tutorials/tree/master/notebooks/pathomics)