Add raffle to the package index (#524)

Author: nedtaylor

data/package_index.yml

@@ -1562,6 +1562,13 @@
   tags: electronic-structure quantum-chemistry casscf
   license: Apache-2.0
 
+- name: raffle
+  github: ExeQuantCode/RAFFLE
+  description: Package for predicting material interface structures
+  categories: scientific
+  tags: material structure phase atomic molecular-modeling
+  license: GPL-3.0
+
 # --- Examples / demos / templates ---
 
 - name: Fortran 2018 examples