Add license

Author: beweber620

index.Rmd

@@ -17,6 +17,10 @@ output:
             <img src="https://datalab.ucdavis.edu/wp-content/uploads/2019/07/datalab-logo-full-color-rgb-1.png" style="height: 100%; width: 100%; object-fit: contain" />
           </a></li>
           <li><a href="./" style="font-size: 18px">Intro to SQL for Querying Databases</a></li>
+        after: |
+        <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" target="_blank">
+          <img alt="CC BY-SA 4.0" src="https://img.shields.io/badge/License-CC%20BY--NC--SA%204.0-lightgrey.svg" style="float: right; padding-right: 10px;" />
+        </a>
         collapse: section
       sharing: no
       view: https://github.com/ucdavisdatalab/workshop_intro_to_sql/blob/master/%s