Add subtitle

Author: jfy133

CITATION.cff

@@ -52,7 +52,7 @@ authors:
     given-names: Christina
     orcid: https://orcid.org/0000-0002-4528-5877
 
-title: "The Little Book of Smiley Plots"
+title: "The Little Book of Smiley Plots: A collection of ancient DNA patterns and their causes"
 version: 2025
 date-released: 2025-09-21
 license: CC0