Let editors define FAQ topics freely instead of a hard-coded map

pb/pb_migrations/collections_schema.json

@@ -393,21 +393,19 @@
         "type": "text"
       },
       {
+        "autogeneratePattern": "",
         "help": "",
         "hidden": false,
         "id": "select2638274075",
-        "maxSelect": 1,
+        "max": 0,
+        "min": 0,
         "name": "topic",
+        "pattern": "",
         "presentable": false,
+        "primaryKey": false,
         "required": true,
         "system": false,
-        "type": "select",
-        "values": [
-          "mensa",
-          "schliessfach",
-          "elterneuro",
-          "elternarbeit"
-        ]
+        "type": "text"
       },
       {
         "help": "",