Completed the port of the buurtnatuur-layer with some fixes for that

Customizations/JSON/FromJSON.ts

@@ -78,6 +78,10 @@ export class FromJSON {
             json.startLat,
             json.startLon,
             new Combine(["<h3>", tr(json.title), "</h3>", tr(json.description)]),
+            undefined,
+            undefined,
+            tr(json.descriptionTail)
+            
         );
 
         layout.widenFactor = json.widenFactor ?? 0.07;

Customizations/JSON/LayoutConfigJson.ts

@@ -48,6 +48,10 @@ export interface LayoutConfigJson {
      */
     description: string | any;
 
+    /**
+     * A part of the description, shown under the login-button.
+     */
+    descriptionTail?: string | any;
 
     /**
      * The icon representing this theme.