Themes(rolling_stock): add preset type selection + fix typo

assets/layers/historic_rolling_stock/historic_rolling_stock.json

@@ -150,6 +150,10 @@
   ],
   "tagRenderings": [
     "images",
+    {
+      "id": "preset_type",
+      "render": "{preset_type_select()}"
+    },
     "wikipedia",
     {
       "id": "model",

src/UI/SpecialVisualisations/UISpecialVisualisations.ts

@@ -21,7 +21,7 @@ class QuestionViz implements SpecialVisualizationSvelte {
     funcName = "questions"
     needsUrls = []
     docs =
-        "The special element which shows the questions which are unkown. Added by default if not yet there"
+        "The special element which shows the questions which are unknown. Added by default if not yet there"
     args = [
         {
             name: "labels",