add tagRendering for start_date

assets/layers/scouting_group/scouting_group.json

@@ -96,6 +96,21 @@
       "id": "association"
     },
     "contact",
+    {
+      "render": {
+        "en": "This group was founded at {start_date}",
+        "de": "Dieser Stamm wurde gegründet am {start_date}"
+      },
+      "question": {
+        "en": "When was this group founded?",
+        "de": "Wann wurde dieser Stamm gegründet?"
+      },
+      "freeform": {
+        "key": "start_date",
+        "type": "date"
+      },
+      "id": "start_date"
+    },
     "questions",
     "mastodon"
   ],