added citydemonstrator to content.json

public/content/content.json

-[{
+[  
+  {
+    "item": {
+      "title": "CityDemonstrator",
+      "project": "iCity Project",
+      "author": {
+        "firstName": "Sven",
+        "lastName": "Schneider",
+        "hftURL": "https://www.hft-stuttgart.de/p/sven-schneider"
+      },
+      "project_year_start": "2021",
+      "project_year_end": "2024",
+      "project_is_on_going": true,
+      "imageLink":"https://citydemonstrator.hft-stuttgart.de/assets/img/iCity_network_1.svg",
+      "keywords":["Smart City","Participation", "LIN Stadt" ],
+      "description_en":"Learn about Intelligent Cities with our City Demonstrator. Find out what makes our cities Liveable, Intelligent and Sustainable - the LIS city.",
+      "description_de":"Erfahren Sie mehr über intelligente Städte mit dem City Demonstrator. Was macht unsere Städte Lebenswert, Intelligent und Nachhaltig - die LIN Stadt."
+    },
+    "refIndex": 5,
+    "links": {
+      "demo": "https://urbanvis.hft-stuttgart.de/Testgebiete.html",      
+      "project":"https://www.hft-stuttgart.de/forschung/projekte/aktuell/inspirer"
+    }
+  }, 
+  {
     "item": {
       "title": "INSPIRER case-studies",
       "project": "INSPIRER",