docs(website): add C4 to sidebar

website/i18n/en.json

@@ -32,6 +32,9 @@
       "nodes/azure": {
         "title": "Azure"
       },
+      "nodes/c4": {
+        "title": "C4"
+      },
       "nodes/custom": {
         "title": "Custom"
       },

website/sidebars.json

@@ -27,6 +27,7 @@
       "nodes/generic",
       "nodes/programming",
       "nodes/saas",
+      "nodes/c4",
       "nodes/custom"
     ]
   }