Add example mmCIF to allow testing of Confal pyramids

CHANGELOG.md

@@ -7,6 +7,7 @@ Note that since we don't clearly distinguish between a public and private interf
 ## [Unreleased]
 - Add custom labels to Confal pyramids
 - Improve naming of some internal types in Confal pyramids extension coordinate
+- Add example mmCIF file with categories necessary to display Confal pyramids
 
 ## [v3.13.0] - 2022-07-24