Update CITATION.cff

Author: florianthiery

CITATION.cff

@@ -26,7 +26,7 @@ keywords:
   - "Linked Open Data"
   - "Ships"
 contact:
-  - affiliation: "RGZM, Mainz Germany"
+  - affiliation: "RGZM, Mainz, Germany"
     email: florian.thiery@rgzm.de
     family-names: Florian
     given-names: Thiery