add german translation for "Calendar"

src/i18n/de.json

@@ -168,6 +168,7 @@
   "By transit": "Mit öffentlichen Verkehrsmitteln",
   "By {group}": "Von {group}",
   "By {username}": "Von {username}",
+  "Calendar": "Kalender",
   "Can be an email or a link, or just plain text.": "Dies kann eine E-Mail-Adresse oder ein Link sein. Oder einfach ein Freitext.",
   "Cancel": "Abbrechen",
   "Cancel anonymous participation": "Anonyme Teilnahme stornieren",

src/i18n/en_US.json

@@ -35,6 +35,7 @@
   "Back to previous page": "Back to previous page",
   "Before you can login, you need to click on the link inside it to validate your account.": "Before you can login, you need to click on the link inside it to validate your account.",
   "By {username}": "By {username}",
+  "Calendar": "Calendar",
   "Cancel anonymous participation": "Cancel anonymous participation",
   "Cancel creation": "Cancel creation",
   "Cancel edition": "Cancel edition",
@@ -1642,4 +1643,4 @@
   "Visit {instance_domain}": "Visit {instance_domain}",
   "Software details: {software_details}": "Software details: {software_details}",
   "Only instances with an application actor can be followed": "Only instances with an application actor can be followed"
-}
+}