Update README.md

Co-authored-by: Nicole Gay, PhD <[email protected]>

README.md

@@ -250,7 +250,7 @@ The code in this package is licensed under the MIT License. Check the file avail
 
 ### Creative Commons Attribution 4.0 International License (Data)
 
-The data included in this package is available under the CC BY 4.0 license. You are free to:
+The data included in this package are available under the CC BY 4.0 license. You are free to:
 - Share: copy and redistribute the material in any medium or format
 - Adapt:remix, transform, and build upon the material for any purpose, even commercially.